text: /**
   * \file psa/crypto.h
   * \brief Platform Security Architecture cryptography module
   */
  /*
   *  Copyright The Mbed TLS Contributors
   *  SPDX-License-Identifier: Apache-2.0
   *
   *  Licensed under the Apache License, Version 2.0 (the "License"); you may
   *  not use this file except in compliance with the License.
   *  You may obtain a copy of the License at
   *
   *  http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   */
  
  #ifndef PSA_CRYPTO_H
  #define PSA_CRYPTO_H
  
  #include "crypto_platform.h"
  
  #include <stddef.h>
  
  #ifdef __DOXYGEN_ONLY__
  /* This __DOXYGEN_ONLY__ block contains mock definitions for things that
   * must be defined in the crypto_platform.h header. These mock definitions
   * are present in this file as a convenience to generate pretty-printed
   * documentation that includes those definitions. */
  
  /** \defgroup platform Implementation-specific definitions
   * @{
   */
  
  /**@}*/
  #endif /* __DOXYGEN_ONLY__ */
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /* The file "crypto_types.h" declares types that encode errors,
   * algorithms, key types, policies, etc. */
  #include "crypto_types.h"
  
  /** \defgroup version API version
   * @{
   */
  
  /**
   * The major version of this implementation of the PSA Crypto API
   */
  #define PSA_CRYPTO_API_VERSION_MAJOR 1
  
  /**
   * The minor version of this implementation of the PSA Crypto API
   */
  #define PSA_CRYPTO_API_VERSION_MINOR 0
  
  /**@}*/
  
  /* The file "crypto_values.h" declares macros to build and analyze values
   * of integral types defined in "crypto_types.h". */
  #include "crypto_values.h"
  
  /** \defgroup initialization Library initialization
   * @{
   */
  
  /**
   * \brief Library initialization.
   *
   * Applications must call this function before calling any other
   * function in this module.
   *
   * Applications may call this function more than once. Once a call
   * succeeds, subsequent calls are guaranteed to succeed.
   *
   * If the application calls other functions before calling psa_crypto_init(),
   * the behavior is undefined. Implementations are encouraged to either perform
   * the operation as if the library had been initialized or to return
   * #PSA_ERROR_BAD_STATE or some other applicable error. In particular,
   * implementations should not return a success status if the lack of
   * initialization may have security implications, for example due to improper
   * seeding of the random number generator.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_INSUFFICIENT_STORAGE
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_DATA_INVALID
   * \retval #PSA_ERROR_DATA_CORRUPT
   */
  psa_status_t psa_crypto_init(void);
  
  /**@}*/
  
  /** \addtogroup attributes
   * @{
   */
  
  /** \def PSA_KEY_ATTRIBUTES_INIT
   *
   * This macro returns a suitable initializer for a key attribute structure
   * of type #psa_key_attributes_t.
   */
  
  /** Return an initial value for a key attributes structure.
   */
  static psa_key_attributes_t psa_key_attributes_init(void);
  
  /** Declare a key as persistent and set its key identifier.
   *
   * If the attribute structure currently declares the key as volatile (which
   * is the default content of an attribute structure), this function sets
   * the lifetime attribute to #PSA_KEY_LIFETIME_PERSISTENT.
   *
   * This function does not access storage, it merely stores the given
   * value in the structure.
   * The persistent key will be written to storage when the attribute
   * structure is passed to a key creation function such as
   * psa_import_key(), psa_generate_key(),
   * psa_key_derivation_output_key() or psa_copy_key().
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate each of its arguments exactly once.
   *
   * \param[out] attributes  The attribute structure to write to.
   * \param key              The persistent identifier for the key.
   */
  static void psa_set_key_id( psa_key_attributes_t *attributes,
                              mbedtls_svc_key_id_t key );
  
  #ifdef MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER
  /** Set the owner identifier of a key.
   *
   * When key identifiers encode key owner identifiers, psa_set_key_id() does
   * not allow to define in key attributes the owner of volatile keys as
   * psa_set_key_id() enforces the key to be persistent.
   *
   * This function allows to set in key attributes the owner identifier of a
   * key. It is intended to be used for volatile keys. For persistent keys,
   * it is recommended to use the PSA Cryptography API psa_set_key_id() to define
   * the owner of a key.
   *
   * \param[out] attributes  The attribute structure to write to.
   * \param owner_id         The key owner identifier.
   */
  static void mbedtls_set_key_owner_id( psa_key_attributes_t *attributes,
                                        mbedtls_key_owner_id_t owner_id );
  #endif
  
  /** Set the location of a persistent key.
   *
   * To make a key persistent, you must give it a persistent key identifier
   * with psa_set_key_id(). By default, a key that has a persistent identifier
   * is stored in the default storage area identifier by
   * #PSA_KEY_LIFETIME_PERSISTENT. Call this function to choose a storage
   * area, or to explicitly declare the key as volatile.
   *
   * This function does not access storage, it merely stores the given
   * value in the structure.
   * The persistent key will be written to storage when the attribute
   * structure is passed to a key creation function such as
   * psa_import_key(), psa_generate_key(),
   * psa_key_derivation_output_key() or psa_copy_key().
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate each of its arguments exactly once.
   *
   * \param[out] attributes       The attribute structure to write to.
   * \param lifetime              The lifetime for the key.
   *                              If this is #PSA_KEY_LIFETIME_VOLATILE, the
   *                              key will be volatile, and the key identifier
   *                              attribute is reset to 0.
   */
  static void psa_set_key_lifetime(psa_key_attributes_t *attributes,
                                   psa_key_lifetime_t lifetime);
  
  /** Retrieve the key identifier from key attributes.
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate its argument exactly once.
   *
   * \param[in] attributes        The key attribute structure to query.
   *
   * \return The persistent identifier stored in the attribute structure.
   *         This value is unspecified if the attribute structure declares
   *         the key as volatile.
   */
  static mbedtls_svc_key_id_t psa_get_key_id(
      const psa_key_attributes_t *attributes);
  
  /** Retrieve the lifetime from key attributes.
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate its argument exactly once.
   *
   * \param[in] attributes        The key attribute structure to query.
   *
   * \return The lifetime value stored in the attribute structure.
   */
  static psa_key_lifetime_t psa_get_key_lifetime(
      const psa_key_attributes_t *attributes);
  
  /** Declare usage flags for a key.
   *
   * Usage flags are part of a key's usage policy. They encode what
   * kind of operations are permitted on the key. For more details,
   * refer to the documentation of the type #psa_key_usage_t.
   *
   * This function overwrites any usage flags
   * previously set in \p attributes.
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate each of its arguments exactly once.
   *
   * \param[out] attributes       The attribute structure to write to.
   * \param usage_flags           The usage flags to write.
   */
  static void psa_set_key_usage_flags(psa_key_attributes_t *attributes,
                                      psa_key_usage_t usage_flags);
  
  /** Retrieve the usage flags from key attributes.
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate its argument exactly once.
   *
   * \param[in] attributes        The key attribute structure to query.
   *
   * \return The usage flags stored in the attribute structure.
   */
  static psa_key_usage_t psa_get_key_usage_flags(
      const psa_key_attributes_t *attributes);
  
  /** Declare the permitted algorithm policy for a key.
   *
   * The permitted algorithm policy of a key encodes which algorithm or
   * algorithms are permitted to be used with this key. The following
   * algorithm policies are supported:
   * - 0 does not allow any cryptographic operation with the key. The key
   *   may be used for non-cryptographic actions such as exporting (if
   *   permitted by the usage flags).
   * - An algorithm value permits this particular algorithm.
   * - An algorithm wildcard built from #PSA_ALG_ANY_HASH allows the specified
   *   signature scheme with any hash algorithm.
   * - An algorithm built from #PSA_ALG_AT_LEAST_THIS_LENGTH_MAC allows
   *   any MAC algorithm from the same base class (e.g. CMAC) which
   *   generates/verifies a MAC length greater than or equal to the length
   *   encoded in the wildcard algorithm.
   * - An algorithm built from #PSA_ALG_AEAD_WITH_AT_LEAST_THIS_LENGTH_TAG
   *   allows any AEAD algorithm from the same base class (e.g. CCM) which
   *   generates/verifies a tag length greater than or equal to the length
   *   encoded in the wildcard algorithm.
   *
   * This function overwrites any algorithm policy
   * previously set in \p attributes.
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate each of its arguments exactly once.
   *
   * \param[out] attributes       The attribute structure to write to.
   * \param alg                   The permitted algorithm policy to write.
   */
  static void psa_set_key_algorithm(psa_key_attributes_t *attributes,
                                    psa_algorithm_t alg);
  
  
  /** Retrieve the algorithm policy from key attributes.
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate its argument exactly once.
   *
   * \param[in] attributes        The key attribute structure to query.
   *
   * \return The algorithm stored in the attribute structure.
   */
  static psa_algorithm_t psa_get_key_algorithm(
      const psa_key_attributes_t *attributes);
  
  /** Declare the type of a key.
   *
   * This function overwrites any key type
   * previously set in \p attributes.
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate each of its arguments exactly once.
   *
   * \param[out] attributes       The attribute structure to write to.
   * \param type                  The key type to write.
   *                              If this is 0, the key type in \p attributes
   *                              becomes unspecified.
   */
  static void psa_set_key_type(psa_key_attributes_t *attributes,
                               psa_key_type_t type);
  
  
  /** Declare the size of a key.
   *
   * This function overwrites any key size previously set in \p attributes.
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate each of its arguments exactly once.
   *
   * \param[out] attributes       The attribute structure to write to.
   * \param bits                  The key size in bits.
   *                              If this is 0, the key size in \p attributes
   *                              becomes unspecified. Keys of size 0 are
   *                              not supported.
   */
  static void psa_set_key_bits(psa_key_attributes_t *attributes,
                               size_t bits);
  
  /** Retrieve the key type from key attributes.
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate its argument exactly once.
   *
   * \param[in] attributes        The key attribute structure to query.
   *
   * \return The key type stored in the attribute structure.
   */
  static psa_key_type_t psa_get_key_type(const psa_key_attributes_t *attributes);
  
  /** Retrieve the key size from key attributes.
   *
   * This function may be declared as `static` (i.e. without external
   * linkage). This function may be provided as a function-like macro,
   * but in this case it must evaluate its argument exactly once.
   *
   * \param[in] attributes        The key attribute structure to query.
   *
   * \return The key size stored in the attribute structure, in bits.
   */
  static size_t psa_get_key_bits(const psa_key_attributes_t *attributes);
  
  /** Retrieve the attributes of a key.
   *
   * This function first resets the attribute structure as with
   * psa_reset_key_attributes(). It then copies the attributes of
   * the given key into the given attribute structure.
   *
   * \note This function may allocate memory or other resources.
   *       Once you have called this function on an attribute structure,
   *       you must call psa_reset_key_attributes() to free these resources.
   *
   * \param[in] key               Identifier of the key to query.
   * \param[in,out] attributes    On success, the attributes of the key.
   *                              On failure, equivalent to a
   *                              freshly-initialized structure.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_DATA_CORRUPT
   * \retval #PSA_ERROR_DATA_INVALID
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_get_key_attributes(mbedtls_svc_key_id_t key,
                                      psa_key_attributes_t *attributes);
  
  /** Reset a key attribute structure to a freshly initialized state.
   *
   * You must initialize the attribute structure as described in the
   * documentation of the type #psa_key_attributes_t before calling this
   * function. Once the structure has been initialized, you may call this
   * function at any time.
   *
   * This function frees any auxiliary resources that the structure
   * may contain.
   *
   * \param[in,out] attributes    The attribute structure to reset.
   */
  void psa_reset_key_attributes(psa_key_attributes_t *attributes);
  
  /**@}*/
  
  /** \defgroup key_management Key management
   * @{
   */
  
  /** Remove non-essential copies of key material from memory.
   *
   * If the key identifier designates a volatile key, this functions does not do
   * anything and returns successfully.
   *
   * If the key identifier designates a persistent key, then this function will
   * free all resources associated with the key in volatile memory. The key
   * data in persistent storage is not affected and the key can still be used.
   *
   * \param key Identifier of the key to purge.
   *
   * \retval #PSA_SUCCESS
   *         The key material will have been removed from memory if it is not
   *         currently required.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not a valid key identifier.
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_purge_key(mbedtls_svc_key_id_t key);
  
  /** Make a copy of a key.
   *
   * Copy key material from one location to another.
   *
   * This function is primarily useful to copy a key from one location
   * to another, since it populates a key using the material from
   * another key which may have a different lifetime.
   *
   * This function may be used to share a key with a different party,
   * subject to implementation-defined restrictions on key sharing.
   *
   * The policy on the source key must have the usage flag
   * #PSA_KEY_USAGE_COPY set.
   * This flag is sufficient to permit the copy if the key has the lifetime
   * #PSA_KEY_LIFETIME_VOLATILE or #PSA_KEY_LIFETIME_PERSISTENT.
   * Some secure elements do not provide a way to copy a key without
   * making it extractable from the secure element. If a key is located
   * in such a secure element, then the key must have both usage flags
   * #PSA_KEY_USAGE_COPY and #PSA_KEY_USAGE_EXPORT in order to make
   * a copy of the key outside the secure element.
   *
   * The resulting key may only be used in a way that conforms to
   * both the policy of the original key and the policy specified in
   * the \p attributes parameter:
   * - The usage flags on the resulting key are the bitwise-and of the
   *   usage flags on the source policy and the usage flags in \p attributes.
   * - If both allow the same algorithm or wildcard-based
   *   algorithm policy, the resulting key has the same algorithm policy.
   * - If either of the policies allows an algorithm and the other policy
   *   allows a wildcard-based algorithm policy that includes this algorithm,
   *   the resulting key allows the same algorithm.
   * - If the policies do not allow any algorithm in common, this function
   *   fails with the status #PSA_ERROR_INVALID_ARGUMENT.
   *
   * The effect of this function on implementation-defined attributes is
   * implementation-defined.
   *
   * \param source_key        The key to copy. It must allow the usage
   *                          #PSA_KEY_USAGE_COPY. If a private or secret key is
   *                          being copied outside of a secure element it must
   *                          also allow #PSA_KEY_USAGE_EXPORT.
   * \param[in] attributes    The attributes for the new key.
   *                          They are used as follows:
   *                          - The key type and size may be 0. If either is
   *                            nonzero, it must match the corresponding
   *                            attribute of the source key.
   *                          - The key location (the lifetime and, for
   *                            persistent keys, the key identifier) is
   *                            used directly.
   *                          - The policy constraints (usage flags and
   *                            algorithm policy) are combined from
   *                            the source key and \p attributes so that
   *                            both sets of restrictions apply, as
   *                            described in the documentation of this function.
   * \param[out] target_key   On success, an identifier for the newly created
   *                          key. For persistent keys, this is the key
   *                          identifier defined in \p attributes.
   *                          \c 0 on failure.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_HANDLE
   *         \p source_key is invalid.
   * \retval #PSA_ERROR_ALREADY_EXISTS
   *         This is an attempt to create a persistent key, and there is
   *         already a persistent key with the given identifier.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The lifetime or identifier in \p attributes are invalid.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The policy constraints on the source and specified in
   *         \p attributes are incompatible.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p attributes specifies a key type or key size
   *         which does not match the attributes of the source key.
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         The source key does not have the #PSA_KEY_USAGE_COPY usage flag.
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         The source key is not exportable and its lifetime does not
   *         allow copying it to the target's lifetime.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_INSUFFICIENT_STORAGE
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_DATA_INVALID
   * \retval #PSA_ERROR_DATA_CORRUPT
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_copy_key(mbedtls_svc_key_id_t source_key,
                            const psa_key_attributes_t *attributes,
                            mbedtls_svc_key_id_t *target_key);
  
  
  /**
   * \brief Destroy a key.
   *
   * This function destroys a key from both volatile
   * memory and, if applicable, non-volatile storage. Implementations shall
   * make a best effort to ensure that that the key material cannot be recovered.
   *
   * This function also erases any metadata such as policies and frees
   * resources associated with the key.
   *
   * If a key is currently in use in a multipart operation, then destroying the
   * key will cause the multipart operation to fail.
   *
   * \param key  Identifier of the key to erase. If this is \c 0, do nothing and
   *             return #PSA_SUCCESS.
   *
   * \retval #PSA_SUCCESS
   *         \p key was a valid identifier and the key material that it
   *         referred to has been erased. Alternatively, \p key is \c 0.
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         The key cannot be erased because it is
   *         read-only, either due to a policy or due to physical restrictions.
   * \retval #PSA_ERROR_INVALID_HANDLE
   *         \p key is not a valid identifier nor \c 0.
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   *         There was an failure in communication with the cryptoprocessor.
   *         The key material may still be present in the cryptoprocessor.
   * \retval #PSA_ERROR_DATA_INVALID
   *         This error is typically a result of either storage corruption on a
   *         cleartext storage backend, or an attempt to read data that was
   *         written by an incompatible version of the library.
   * \retval #PSA_ERROR_STORAGE_FAILURE
   *         The storage is corrupted. Implementations shall make a best effort
   *         to erase key material even in this stage, however applications
   *         should be aware that it may be impossible to guarantee that the
   *         key material is not recoverable in such cases.
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   *         An unexpected condition which is not a storage corruption or
   *         a communication failure occurred. The cryptoprocessor may have
   *         been compromised.
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_destroy_key(mbedtls_svc_key_id_t key);
  
  /**@}*/
  
  /** \defgroup import_export Key import and export
   * @{
   */
  
  /**
   * \brief Import a key in binary format.
   *
   * This function supports any output from psa_export_key(). Refer to the
   * documentation of psa_export_public_key() for the format of public keys
   * and to the documentation of psa_export_key() for the format for
   * other key types.
   *
   * The key data determines the key size. The attributes may optionally
   * specify a key size; in this case it must match the size determined
   * from the key data. A key size of 0 in \p attributes indicates that
   * the key size is solely determined by the key data.
   *
   * Implementations must reject an attempt to import a key of size 0.
   *
   * This specification supports a single format for each key type.
   * Implementations may support other formats as long as the standard
   * format is supported. Implementations that support other formats
   * should ensure that the formats are clearly unambiguous so as to
   * minimize the risk that an invalid input is accidentally interpreted
   * according to a different format.
   *
   * \param[in] attributes    The attributes for the new key.
   *                          The key size is always determined from the
   *                          \p data buffer.
   *                          If the key size in \p attributes is nonzero,
   *                          it must be equal to the size from \p data.
   * \param[out] key          On success, an identifier to the newly created key.
   *                          For persistent keys, this is the key identifier
   *                          defined in \p attributes.
   *                          \c 0 on failure.
   * \param[in] data    Buffer containing the key data. The content of this
   *                    buffer is interpreted according to the type declared
   *                    in \p attributes.
   *                    All implementations must support at least the format
   *                    described in the documentation
   *                    of psa_export_key() or psa_export_public_key() for
   *                    the chosen type. Implementations may allow other
   *                    formats, but should be conservative: implementations
   *                    should err on the side of rejecting content if it
   *                    may be erroneous (e.g. wrong type or truncated data).
   * \param data_length Size of the \p data buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   *         If the key is persistent, the key material and the key's metadata
   *         have been saved to persistent storage.
   * \retval #PSA_ERROR_ALREADY_EXISTS
   *         This is an attempt to create a persistent key, and there is
   *         already a persistent key with the given identifier.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         The key type or key size is not supported, either by the
   *         implementation in general or in this particular persistent location.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The key attributes, as a whole, are invalid.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The key data is not correctly formatted.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The size in \p attributes is nonzero and does not match the size
   *         of the key data.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_INSUFFICIENT_STORAGE
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_DATA_CORRUPT
   * \retval #PSA_ERROR_DATA_INVALID
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_import_key(const psa_key_attributes_t *attributes,
                              const uint8_t *data,
                              size_t data_length,
                              mbedtls_svc_key_id_t *key);
  
  
  
  /**
   * \brief Export a key in binary format.
   *
   * The output of this function can be passed to psa_import_key() to
   * create an equivalent object.
   *
   * If the implementation of psa_import_key() supports other formats
   * beyond the format specified here, the output from psa_export_key()
   * must use the representation specified here, not the original
   * representation.
   *
   * For standard key types, the output format is as follows:
   *
   * - For symmetric keys (including MAC keys), the format is the
   *   raw bytes of the key.
   * - For DES, the key data consists of 8 bytes. The parity bits must be
   *   correct.
   * - For Triple-DES, the format is the concatenation of the
   *   two or three DES keys.
   * - For RSA key pairs (#PSA_KEY_TYPE_RSA_KEY_PAIR), the format
   *   is the non-encrypted DER encoding of the representation defined by
   *   PKCS\#1 (RFC 8017) as `RSAPrivateKey`, version 0.
   *   ```
   *   RSAPrivateKey ::= SEQUENCE {
   *       version             INTEGER,  -- must be 0
   *       modulus             INTEGER,  -- n
   *       publicExponent      INTEGER,  -- e
   *       privateExponent     INTEGER,  -- d
   *       prime1              INTEGER,  -- p
   *       prime2              INTEGER,  -- q
   *       exponent1           INTEGER,  -- d mod (p-1)
   *       exponent2           INTEGER,  -- d mod (q-1)
   *       coefficient         INTEGER,  -- (inverse of q) mod p
   *   }
   *   ```
   * - For elliptic curve key pairs (key types for which
   *   #PSA_KEY_TYPE_IS_ECC_KEY_PAIR is true), the format is
   *   a representation of the private value as a `ceiling(m/8)`-byte string
   *   where `m` is the bit size associated with the curve, i.e. the bit size
   *   of the order of the curve's coordinate field. This byte string is
   *   in little-endian order for Montgomery curves (curve types
   *   `PSA_ECC_FAMILY_CURVEXXX`), and in big-endian order for Weierstrass
   *   curves (curve types `PSA_ECC_FAMILY_SECTXXX`, `PSA_ECC_FAMILY_SECPXXX`
   *   and `PSA_ECC_FAMILY_BRAINPOOL_PXXX`).
   *   For Weierstrass curves, this is the content of the `privateKey` field of
   *   the `ECPrivateKey` format defined by RFC 5915.  For Montgomery curves,
   *   the format is defined by RFC 7748, and output is masked according to §5.
   *   For twisted Edwards curves, the private key is as defined by RFC 8032
   *   (a 32-byte string for Edwards25519, a 57-byte string for Edwards448).
   * - For Diffie-Hellman key exchange key pairs (key types for which
   *   #PSA_KEY_TYPE_IS_DH_KEY_PAIR is true), the
   *   format is the representation of the private key `x` as a big-endian byte
   *   string. The length of the byte string is the private key size in bytes
   *   (leading zeroes are not stripped).
   * - For public keys (key types for which #PSA_KEY_TYPE_IS_PUBLIC_KEY is
   *   true), the format is the same as for psa_export_public_key().
   *
   * The policy on the key must have the usage flag #PSA_KEY_USAGE_EXPORT set.
   *
   * \param key               Identifier of the key to export. It must allow the
   *                          usage #PSA_KEY_USAGE_EXPORT, unless it is a public
   *                          key.
   * \param[out] data         Buffer where the key data is to be written.
   * \param data_size         Size of the \p data buffer in bytes.
   * \param[out] data_length  On success, the number of bytes
   *                          that make up the key data.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         The key does not have the #PSA_KEY_USAGE_EXPORT flag.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p data buffer is too small. You can determine a
   *         sufficient buffer size by calling
   *         #PSA_EXPORT_KEY_OUTPUT_SIZE(\c type, \c bits)
   *         where \c type is the key type
   *         and \c bits is the key size in bits.
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_export_key(mbedtls_svc_key_id_t key,
                              uint8_t *data,
                              size_t data_size,
                              size_t *data_length);
  
  /**
   * \brief Export a public key or the public part of a key pair in binary format.
   *
   * The output of this function can be passed to psa_import_key() to
   * create an object that is equivalent to the public key.
   *
   * This specification supports a single format for each key type.
   * Implementations may support other formats as long as the standard
   * format is supported. Implementations that support other formats
   * should ensure that the formats are clearly unambiguous so as to
   * minimize the risk that an invalid input is accidentally interpreted
   * according to a different format.
   *
   * For standard key types, the output format is as follows:
   * - For RSA public keys (#PSA_KEY_TYPE_RSA_PUBLIC_KEY), the DER encoding of
   *   the representation defined by RFC 3279 &sect;2.3.1 as `RSAPublicKey`.
   *   ```
   *   RSAPublicKey ::= SEQUENCE {
   *      modulus            INTEGER,    -- n
   *      publicExponent     INTEGER  }  -- e
   *   ```
   * - For elliptic curve keys on a twisted Edwards curve (key types for which
   *   #PSA_KEY_TYPE_IS_ECC_PUBLIC_KEY is true and #PSA_KEY_TYPE_ECC_GET_FAMILY
   *   returns #PSA_ECC_FAMILY_TWISTED_EDWARDS), the public key is as defined
   *   by RFC 8032
   *   (a 32-byte string for Edwards25519, a 57-byte string for Edwards448).
   * - For other elliptic curve public keys (key types for which
   *   #PSA_KEY_TYPE_IS_ECC_PUBLIC_KEY is true), the format is the uncompressed
   *   representation defined by SEC1 &sect;2.3.3 as the content of an ECPoint.
   *   Let `m` be the bit size associated with the curve, i.e. the bit size of
   *   `q` for a curve over `F_q`. The representation consists of:
   *      - The byte 0x04;
   *      - `x_P` as a `ceiling(m/8)`-byte string, big-endian;
   *      - `y_P` as a `ceiling(m/8)`-byte string, big-endian.
   * - For Diffie-Hellman key exchange public keys (key types for which
   *   #PSA_KEY_TYPE_IS_DH_PUBLIC_KEY is true),
   *   the format is the representation of the public key `y = g^x mod p` as a
   *   big-endian byte string. The length of the byte string is the length of the
   *   base prime `p` in bytes.
   *
   * Exporting a public key object or the public part of a key pair is
   * always permitted, regardless of the key's usage flags.
   *
   * \param key               Identifier of the key to export.
   * \param[out] data         Buffer where the key data is to be written.
   * \param data_size         Size of the \p data buffer in bytes.
   * \param[out] data_length  On success, the number of bytes
   *                          that make up the key data.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The key is neither a public key nor a key pair.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p data buffer is too small. You can determine a
   *         sufficient buffer size by calling
   *         #PSA_EXPORT_KEY_OUTPUT_SIZE(#PSA_KEY_TYPE_PUBLIC_KEY_OF_KEY_PAIR(\c type), \c bits)
   *         where \c type is the key type
   *         and \c bits is the key size in bits.
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_export_public_key(mbedtls_svc_key_id_t key,
                                     uint8_t *data,
                                     size_t data_size,
                                     size_t *data_length);
  
  
  
  /**@}*/
  
  /** \defgroup hash Message digests
   * @{
   */
  
  /** Calculate the hash (digest) of a message.
   *
   * \note To verify the hash of a message against an
   *       expected value, use psa_hash_compare() instead.
   *
   * \param alg               The hash algorithm to compute (\c PSA_ALG_XXX value
   *                          such that #PSA_ALG_IS_HASH(\p alg) is true).
   * \param[in] input         Buffer containing the message to hash.
   * \param input_length      Size of the \p input buffer in bytes.
   * \param[out] hash         Buffer where the hash is to be written.
   * \param hash_size         Size of the \p hash buffer in bytes.
   * \param[out] hash_length  On success, the number of bytes
   *                          that make up the hash value. This is always
   *                          #PSA_HASH_LENGTH(\p alg).
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not a hash algorithm.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         \p hash_size is too small
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_hash_compute(psa_algorithm_t alg,
                                const uint8_t *input,
                                size_t input_length,
                                uint8_t *hash,
                                size_t hash_size,
                                size_t *hash_length);
  
  /** Calculate the hash (digest) of a message and compare it with a
   * reference value.
   *
   * \param alg               The hash algorithm to compute (\c PSA_ALG_XXX value
   *                          such that #PSA_ALG_IS_HASH(\p alg) is true).
   * \param[in] input         Buffer containing the message to hash.
   * \param input_length      Size of the \p input buffer in bytes.
   * \param[out] hash         Buffer containing the expected hash value.
   * \param hash_length       Size of the \p hash buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         The expected hash is identical to the actual hash of the input.
   * \retval #PSA_ERROR_INVALID_SIGNATURE
   *         The hash of the message was calculated successfully, but it
   *         differs from the expected hash.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not a hash algorithm.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p input_length or \p hash_length do not match the hash size for \p alg
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_hash_compare(psa_algorithm_t alg,
                                const uint8_t *input,
                                size_t input_length,
                                const uint8_t *hash,
                                size_t hash_length);
  
  /** The type of the state data structure for multipart hash operations.
   *
   * Before calling any function on a hash operation object, the application must
   * initialize it by any of the following means:
   * - Set the structure to all-bits-zero, for example:
   *   \code
   *   psa_hash_operation_t operation;
   *   memset(&operation, 0, sizeof(operation));
   *   \endcode
   * - Initialize the structure to logical zero values, for example:
   *   \code
   *   psa_hash_operation_t operation = {0};
   *   \endcode
   * - Initialize the structure to the initializer #PSA_HASH_OPERATION_INIT,
   *   for example:
   *   \code
   *   psa_hash_operation_t operation = PSA_HASH_OPERATION_INIT;
   *   \endcode
   * - Assign the result of the function psa_hash_operation_init()
   *   to the structure, for example:
   *   \code
   *   psa_hash_operation_t operation;
   *   operation = psa_hash_operation_init();
   *   \endcode
   *
   * This is an implementation-defined \c struct. Applications should not
   * make any assumptions about the content of this structure.
   * Implementation details can change in future versions without notice. */
  typedef struct psa_hash_operation_s psa_hash_operation_t;
  
  /** \def PSA_HASH_OPERATION_INIT
   *
   * This macro returns a suitable initializer for a hash operation object
   * of type #psa_hash_operation_t.
   */
  
  /** Return an initial value for a hash operation object.
   */
  static psa_hash_operation_t psa_hash_operation_init(void);
  
  /** Set up a multipart hash operation.
   *
   * The sequence of operations to calculate a hash (message digest)
   * is as follows:
   * -# Allocate an operation object which will be passed to all the functions
   *    listed here.
   * -# Initialize the operation object with one of the methods described in the
   *    documentation for #psa_hash_operation_t, e.g. #PSA_HASH_OPERATION_INIT.
   * -# Call psa_hash_setup() to specify the algorithm.
   * -# Call psa_hash_update() zero, one or more times, passing a fragment
   *    of the message each time. The hash that is calculated is the hash
   *    of the concatenation of these messages in order.
   * -# To calculate the hash, call psa_hash_finish().
   *    To compare the hash with an expected value, call psa_hash_verify().
   *
   * If an error occurs at any step after a call to psa_hash_setup(), the
   * operation will need to be reset by a call to psa_hash_abort(). The
   * application may call psa_hash_abort() at any time after the operation
   * has been initialized.
   *
   * After a successful call to psa_hash_setup(), the application must
   * eventually terminate the operation. The following events terminate an
   * operation:
   * - A successful call to psa_hash_finish() or psa_hash_verify().
   * - A call to psa_hash_abort().
   *
   * \param[in,out] operation The operation object to set up. It must have
   *                          been initialized as per the documentation for
   *                          #psa_hash_operation_t and not yet in use.
   * \param alg               The hash algorithm to compute (\c PSA_ALG_XXX value
   *                          such that #PSA_ALG_IS_HASH(\p alg) is true).
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not a supported hash algorithm.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p alg is not a hash algorithm.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be inactive).
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_hash_setup(psa_hash_operation_t *operation,
                              psa_algorithm_t alg);
  
  /** Add a message fragment to a multipart hash operation.
   *
   * The application must call psa_hash_setup() before calling this function.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_hash_abort().
   *
   * \param[in,out] operation Active hash operation.
   * \param[in] input         Buffer containing the message fragment to hash.
   * \param input_length      Size of the \p input buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it muct be active).
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_hash_update(psa_hash_operation_t *operation,
                               const uint8_t *input,
                               size_t input_length);
  
  /** Finish the calculation of the hash of a message.
   *
   * The application must call psa_hash_setup() before calling this function.
   * This function calculates the hash of the message formed by concatenating
   * the inputs passed to preceding calls to psa_hash_update().
   *
   * When this function returns successfuly, the operation becomes inactive.
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_hash_abort().
   *
   * \warning Applications should not call this function if they expect
   *          a specific value for the hash. Call psa_hash_verify() instead.
   *          Beware that comparing integrity or authenticity data such as
   *          hash values with a function such as \c memcmp is risky
   *          because the time taken by the comparison may leak information
   *          about the hashed data which could allow an attacker to guess
   *          a valid hash and thereby bypass security controls.
   *
   * \param[in,out] operation     Active hash operation.
   * \param[out] hash             Buffer where the hash is to be written.
   * \param hash_size             Size of the \p hash buffer in bytes.
   * \param[out] hash_length      On success, the number of bytes
   *                              that make up the hash value. This is always
   *                              #PSA_HASH_LENGTH(\c alg) where \c alg is the
   *                              hash algorithm that is calculated.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active).
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p hash buffer is too small. You can determine a
   *         sufficient buffer size by calling #PSA_HASH_LENGTH(\c alg)
   *         where \c alg is the hash algorithm that is calculated.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_hash_finish(psa_hash_operation_t *operation,
                               uint8_t *hash,
                               size_t hash_size,
                               size_t *hash_length);
  
  /** Finish the calculation of the hash of a message and compare it with
   * an expected value.
   *
   * The application must call psa_hash_setup() before calling this function.
   * This function calculates the hash of the message formed by concatenating
   * the inputs passed to preceding calls to psa_hash_update(). It then
   * compares the calculated hash with the expected hash passed as a
   * parameter to this function.
   *
   * When this function returns successfuly, the operation becomes inactive.
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_hash_abort().
   *
   * \note Implementations shall make the best effort to ensure that the
   * comparison between the actual hash and the expected hash is performed
   * in constant time.
   *
   * \param[in,out] operation     Active hash operation.
   * \param[in] hash              Buffer containing the expected hash value.
   * \param hash_length           Size of the \p hash buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         The expected hash is identical to the actual hash of the message.
   * \retval #PSA_ERROR_INVALID_SIGNATURE
   *         The hash of the message was calculated successfully, but it
   *         differs from the expected hash.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active).
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_hash_verify(psa_hash_operation_t *operation,
                               const uint8_t *hash,
                               size_t hash_length);
  
  /** Abort a hash operation.
   *
   * Aborting an operation frees all associated resources except for the
   * \p operation structure itself. Once aborted, the operation object
   * can be reused for another operation by calling
   * psa_hash_setup() again.
   *
   * You may call this function any time after the operation object has
   * been initialized by one of the methods described in #psa_hash_operation_t.
   *
   * In particular, calling psa_hash_abort() after the operation has been
   * terminated by a call to psa_hash_abort(), psa_hash_finish() or
   * psa_hash_verify() is safe and has no effect.
   *
   * \param[in,out] operation     Initialized hash operation.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_hash_abort(psa_hash_operation_t *operation);
  
  /** Clone a hash operation.
   *
   * This function copies the state of an ongoing hash operation to
   * a new operation object. In other words, this function is equivalent
   * to calling psa_hash_setup() on \p target_operation with the same
   * algorithm that \p source_operation was set up for, then
   * psa_hash_update() on \p target_operation with the same input that
   * that was passed to \p source_operation. After this function returns, the
   * two objects are independent, i.e. subsequent calls involving one of
   * the objects do not affect the other object.
   *
   * \param[in] source_operation      The active hash operation to clone.
   * \param[in,out] target_operation  The operation object to set up.
   *                                  It must be initialized but not active.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_BAD_STATE
   *         The \p source_operation state is not valid (it must be active).
   * \retval #PSA_ERROR_BAD_STATE
   *         The \p target_operation state is not valid (it must be inactive).
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_hash_clone(const psa_hash_operation_t *source_operation,
                              psa_hash_operation_t *target_operation);
  
  /**@}*/
  
  /** \defgroup MAC Message authentication codes
   * @{
   */
  
  /** Calculate the MAC (message authentication code) of a message.
   *
   * \note To verify the MAC of a message against an
   *       expected value, use psa_mac_verify() instead.
   *       Beware that comparing integrity or authenticity data such as
   *       MAC values with a function such as \c memcmp is risky
   *       because the time taken by the comparison may leak information
   *       about the MAC value which could allow an attacker to guess
   *       a valid MAC and thereby bypass security controls.
   *
   * \param key               Identifier of the key to use for the operation. It
   *                          must allow the usage PSA_KEY_USAGE_SIGN_MESSAGE.
   * \param alg               The MAC algorithm to compute (\c PSA_ALG_XXX value
   *                          such that #PSA_ALG_IS_MAC(\p alg) is true).
   * \param[in] input         Buffer containing the input message.
   * \param input_length      Size of the \p input buffer in bytes.
   * \param[out] mac          Buffer where the MAC value is to be written.
   * \param mac_size          Size of the \p mac buffer in bytes.
   * \param[out] mac_length   On success, the number of bytes
   *                          that make up the MAC value.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not a MAC algorithm.
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         \p mac_size is too small
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   *         The key could not be retrieved from storage.
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_mac_compute(mbedtls_svc_key_id_t key,
                               psa_algorithm_t alg,
                               const uint8_t *input,
                               size_t input_length,
                               uint8_t *mac,
                               size_t mac_size,
                               size_t *mac_length);
  
  /** Calculate the MAC of a message and compare it with a reference value.
   *
   * \param key               Identifier of the key to use for the operation. It
   *                          must allow the usage PSA_KEY_USAGE_VERIFY_MESSAGE.
   * \param alg               The MAC algorithm to compute (\c PSA_ALG_XXX value
   *                          such that #PSA_ALG_IS_MAC(\p alg) is true).
   * \param[in] input         Buffer containing the input message.
   * \param input_length      Size of the \p input buffer in bytes.
   * \param[out] mac          Buffer containing the expected MAC value.
   * \param mac_length        Size of the \p mac buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         The expected MAC is identical to the actual MAC of the input.
   * \retval #PSA_ERROR_INVALID_SIGNATURE
   *         The MAC of the message was calculated successfully, but it
   *         differs from the expected value.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not a MAC algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   *         The key could not be retrieved from storage.
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_mac_verify(mbedtls_svc_key_id_t key,
                              psa_algorithm_t alg,
                              const uint8_t *input,
                              size_t input_length,
                              const uint8_t *mac,
                              size_t mac_length);
  
  /** The type of the state data structure for multipart MAC operations.
   *
   * Before calling any function on a MAC operation object, the application must
   * initialize it by any of the following means:
   * - Set the structure to all-bits-zero, for example:
   *   \code
   *   psa_mac_operation_t operation;
   *   memset(&operation, 0, sizeof(operation));
   *   \endcode
   * - Initialize the structure to logical zero values, for example:
   *   \code
   *   psa_mac_operation_t operation = {0};
   *   \endcode
   * - Initialize the structure to the initializer #PSA_MAC_OPERATION_INIT,
   *   for example:
   *   \code
   *   psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
   *   \endcode
   * - Assign the result of the function psa_mac_operation_init()
   *   to the structure, for example:
   *   \code
   *   psa_mac_operation_t operation;
   *   operation = psa_mac_operation_init();
   *   \endcode
   *
   *
   * This is an implementation-defined \c struct. Applications should not
   * make any assumptions about the content of this structure.
   * Implementation details can change in future versions without notice. */
  typedef struct psa_mac_operation_s psa_mac_operation_t;
  
  /** \def PSA_MAC_OPERATION_INIT
   *
   * This macro returns a suitable initializer for a MAC operation object of type
   * #psa_mac_operation_t.
   */
  
  /** Return an initial value for a MAC operation object.
   */
  static psa_mac_operation_t psa_mac_operation_init(void);
  
  /** Set up a multipart MAC calculation operation.
   *
   * This function sets up the calculation of the MAC
   * (message authentication code) of a byte string.
   * To verify the MAC of a message against an
   * expected value, use psa_mac_verify_setup() instead.
   *
   * The sequence of operations to calculate a MAC is as follows:
   * -# Allocate an operation object which will be passed to all the functions
   *    listed here.
   * -# Initialize the operation object with one of the methods described in the
   *    documentation for #psa_mac_operation_t, e.g. #PSA_MAC_OPERATION_INIT.
   * -# Call psa_mac_sign_setup() to specify the algorithm and key.
   * -# Call psa_mac_update() zero, one or more times, passing a fragment
   *    of the message each time. The MAC that is calculated is the MAC
   *    of the concatenation of these messages in order.
   * -# At the end of the message, call psa_mac_sign_finish() to finish
   *    calculating the MAC value and retrieve it.
   *
   * If an error occurs at any step after a call to psa_mac_sign_setup(), the
   * operation will need to be reset by a call to psa_mac_abort(). The
   * application may call psa_mac_abort() at any time after the operation
   * has been initialized.
   *
   * After a successful call to psa_mac_sign_setup(), the application must
   * eventually terminate the operation through one of the following methods:
   * - A successful call to psa_mac_sign_finish().
   * - A call to psa_mac_abort().
   *
   * \param[in,out] operation The operation object to set up. It must have
   *                          been initialized as per the documentation for
   *                          #psa_mac_operation_t and not yet in use.
   * \param key               Identifier of the key to use for the operation. It
   *                          must remain valid until the operation terminates.
   *                          It must allow the usage PSA_KEY_USAGE_SIGN_MESSAGE.
   * \param alg               The MAC algorithm to compute (\c PSA_ALG_XXX value
   *                          such that #PSA_ALG_IS_MAC(\p alg) is true).
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not a MAC algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   *         The key could not be retrieved from storage.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be inactive).
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_mac_sign_setup(psa_mac_operation_t *operation,
                                  mbedtls_svc_key_id_t key,
                                  psa_algorithm_t alg);
  
  /** Set up a multipart MAC verification operation.
   *
   * This function sets up the verification of the MAC
   * (message authentication code) of a byte string against an expected value.
   *
   * The sequence of operations to verify a MAC is as follows:
   * -# Allocate an operation object which will be passed to all the functions
   *    listed here.
   * -# Initialize the operation object with one of the methods described in the
   *    documentation for #psa_mac_operation_t, e.g. #PSA_MAC_OPERATION_INIT.
   * -# Call psa_mac_verify_setup() to specify the algorithm and key.
   * -# Call psa_mac_update() zero, one or more times, passing a fragment
   *    of the message each time. The MAC that is calculated is the MAC
   *    of the concatenation of these messages in order.
   * -# At the end of the message, call psa_mac_verify_finish() to finish
   *    calculating the actual MAC of the message and verify it against
   *    the expected value.
   *
   * If an error occurs at any step after a call to psa_mac_verify_setup(), the
   * operation will need to be reset by a call to psa_mac_abort(). The
   * application may call psa_mac_abort() at any time after the operation
   * has been initialized.
   *
   * After a successful call to psa_mac_verify_setup(), the application must
   * eventually terminate the operation through one of the following methods:
   * - A successful call to psa_mac_verify_finish().
   * - A call to psa_mac_abort().
   *
   * \param[in,out] operation The operation object to set up. It must have
   *                          been initialized as per the documentation for
   *                          #psa_mac_operation_t and not yet in use.
   * \param key               Identifier of the key to use for the operation. It
   *                          must remain valid until the operation terminates.
   *                          It must allow the usage
   *                          PSA_KEY_USAGE_VERIFY_MESSAGE.
   * \param alg               The MAC algorithm to compute (\c PSA_ALG_XXX value
   *                          such that #PSA_ALG_IS_MAC(\p alg) is true).
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \c key is not compatible with \c alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \c alg is not supported or is not a MAC algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   *         The key could not be retrieved from storage
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be inactive).
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_mac_verify_setup(psa_mac_operation_t *operation,
                                    mbedtls_svc_key_id_t key,
                                    psa_algorithm_t alg);
  
  /** Add a message fragment to a multipart MAC operation.
   *
   * The application must call psa_mac_sign_setup() or psa_mac_verify_setup()
   * before calling this function.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_mac_abort().
   *
   * \param[in,out] operation Active MAC operation.
   * \param[in] input         Buffer containing the message fragment to add to
   *                          the MAC calculation.
   * \param input_length      Size of the \p input buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active).
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_mac_update(psa_mac_operation_t *operation,
                              const uint8_t *input,
                              size_t input_length);
  
  /** Finish the calculation of the MAC of a message.
   *
   * The application must call psa_mac_sign_setup() before calling this function.
   * This function calculates the MAC of the message formed by concatenating
   * the inputs passed to preceding calls to psa_mac_update().
   *
   * When this function returns successfuly, the operation becomes inactive.
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_mac_abort().
   *
   * \warning Applications should not call this function if they expect
   *          a specific value for the MAC. Call psa_mac_verify_finish() instead.
   *          Beware that comparing integrity or authenticity data such as
   *          MAC values with a function such as \c memcmp is risky
   *          because the time taken by the comparison may leak information
   *          about the MAC value which could allow an attacker to guess
   *          a valid MAC and thereby bypass security controls.
   *
   * \param[in,out] operation Active MAC operation.
   * \param[out] mac          Buffer where the MAC value is to be written.
   * \param mac_size          Size of the \p mac buffer in bytes.
   * \param[out] mac_length   On success, the number of bytes
   *                          that make up the MAC value. This is always
   *                          #PSA_MAC_LENGTH(\c key_type, \c key_bits, \c alg)
   *                          where \c key_type and \c key_bits are the type and
   *                          bit-size respectively of the key and \c alg is the
   *                          MAC algorithm that is calculated.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be an active mac sign
   *         operation).
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p mac buffer is too small. You can determine a
   *         sufficient buffer size by calling PSA_MAC_LENGTH().
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_mac_sign_finish(psa_mac_operation_t *operation,
                                   uint8_t *mac,
                                   size_t mac_size,
                                   size_t *mac_length);
  
  /** Finish the calculation of the MAC of a message and compare it with
   * an expected value.
   *
   * The application must call psa_mac_verify_setup() before calling this function.
   * This function calculates the MAC of the message formed by concatenating
   * the inputs passed to preceding calls to psa_mac_update(). It then
   * compares the calculated MAC with the expected MAC passed as a
   * parameter to this function.
   *
   * When this function returns successfuly, the operation becomes inactive.
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_mac_abort().
   *
   * \note Implementations shall make the best effort to ensure that the
   * comparison between the actual MAC and the expected MAC is performed
   * in constant time.
   *
   * \param[in,out] operation Active MAC operation.
   * \param[in] mac           Buffer containing the expected MAC value.
   * \param mac_length        Size of the \p mac buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         The expected MAC is identical to the actual MAC of the message.
   * \retval #PSA_ERROR_INVALID_SIGNATURE
   *         The MAC of the message was calculated successfully, but it
   *         differs from the expected MAC.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be an active mac verify
   *         operation).
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_mac_verify_finish(psa_mac_operation_t *operation,
                                     const uint8_t *mac,
                                     size_t mac_length);
  
  /** Abort a MAC operation.
   *
   * Aborting an operation frees all associated resources except for the
   * \p operation structure itself. Once aborted, the operation object
   * can be reused for another operation by calling
   * psa_mac_sign_setup() or psa_mac_verify_setup() again.
   *
   * You may call this function any time after the operation object has
   * been initialized by one of the methods described in #psa_mac_operation_t.
   *
   * In particular, calling psa_mac_abort() after the operation has been
   * terminated by a call to psa_mac_abort(), psa_mac_sign_finish() or
   * psa_mac_verify_finish() is safe and has no effect.
   *
   * \param[in,out] operation Initialized MAC operation.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_mac_abort(psa_mac_operation_t *operation);
  
  /**@}*/
  
  /** \defgroup cipher Symmetric ciphers
   * @{
   */
  
  /** Encrypt a message using a symmetric cipher.
   *
   * This function encrypts a message with a random IV (initialization
   * vector). Use the multipart operation interface with a
   * #psa_cipher_operation_t object to provide other forms of IV.
   *
   * \param key                   Identifier of the key to use for the operation.
   *                              It must allow the usage #PSA_KEY_USAGE_ENCRYPT.
   * \param alg                   The cipher algorithm to compute
   *                              (\c PSA_ALG_XXX value such that
   *                              #PSA_ALG_IS_CIPHER(\p alg) is true).
   * \param[in] input             Buffer containing the message to encrypt.
   * \param input_length          Size of the \p input buffer in bytes.
   * \param[out] output           Buffer where the output is to be written.
   *                              The output contains the IV followed by
   *                              the ciphertext proper.
   * \param output_size           Size of the \p output buffer in bytes.
   * \param[out] output_length    On success, the number of bytes
   *                              that make up the output.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not a cipher algorithm.
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_cipher_encrypt(mbedtls_svc_key_id_t key,
                                  psa_algorithm_t alg,
                                  const uint8_t *input,
                                  size_t input_length,
                                  uint8_t *output,
                                  size_t output_size,
                                  size_t *output_length);
  
  /** Decrypt a message using a symmetric cipher.
   *
   * This function decrypts a message encrypted with a symmetric cipher.
   *
   * \param key                   Identifier of the key to use for the operation.
   *                              It must remain valid until the operation
   *                              terminates. It must allow the usage
   *                              #PSA_KEY_USAGE_DECRYPT.
   * \param alg                   The cipher algorithm to compute
   *                              (\c PSA_ALG_XXX value such that
   *                              #PSA_ALG_IS_CIPHER(\p alg) is true).
   * \param[in] input             Buffer containing the message to decrypt.
   *                              This consists of the IV followed by the
   *                              ciphertext proper.
   * \param input_length          Size of the \p input buffer in bytes.
   * \param[out] output           Buffer where the plaintext is to be written.
   * \param output_size           Size of the \p output buffer in bytes.
   * \param[out] output_length    On success, the number of bytes
   *                              that make up the output.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not a cipher algorithm.
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_cipher_decrypt(mbedtls_svc_key_id_t key,
                                  psa_algorithm_t alg,
                                  const uint8_t *input,
                                  size_t input_length,
                                  uint8_t *output,
                                  size_t output_size,
                                  size_t *output_length);
  
  /** The type of the state data structure for multipart cipher operations.
   *
   * Before calling any function on a cipher operation object, the application
   * must initialize it by any of the following means:
   * - Set the structure to all-bits-zero, for example:
   *   \code
   *   psa_cipher_operation_t operation;
   *   memset(&operation, 0, sizeof(operation));
   *   \endcode
   * - Initialize the structure to logical zero values, for example:
   *   \code
   *   psa_cipher_operation_t operation = {0};
   *   \endcode
   * - Initialize the structure to the initializer #PSA_CIPHER_OPERATION_INIT,
   *   for example:
   *   \code
   *   psa_cipher_operation_t operation = PSA_CIPHER_OPERATION_INIT;
   *   \endcode
   * - Assign the result of the function psa_cipher_operation_init()
   *   to the structure, for example:
   *   \code
   *   psa_cipher_operation_t operation;
   *   operation = psa_cipher_operation_init();
   *   \endcode
   *
   * This is an implementation-defined \c struct. Applications should not
   * make any assumptions about the content of this structure.
   * Implementation details can change in future versions without notice. */
  typedef struct psa_cipher_operation_s psa_cipher_operation_t;
  
  /** \def PSA_CIPHER_OPERATION_INIT
   *
   * This macro returns a suitable initializer for a cipher operation object of
   * type #psa_cipher_operation_t.
   */
  
  /** Return an initial value for a cipher operation object.
   */
  static psa_cipher_operation_t psa_cipher_operation_init(void);
  
  /** Set the key for a multipart symmetric encryption operation.
   *
   * The sequence of operations to encrypt a message with a symmetric cipher
   * is as follows:
   * -# Allocate an operation object which will be passed to all the functions
   *    listed here.
   * -# Initialize the operation object with one of the methods described in the
   *    documentation for #psa_cipher_operation_t, e.g.
   *    #PSA_CIPHER_OPERATION_INIT.
   * -# Call psa_cipher_encrypt_setup() to specify the algorithm and key.
   * -# Call either psa_cipher_generate_iv() or psa_cipher_set_iv() to
   *    generate or set the IV (initialization vector). You should use
   *    psa_cipher_generate_iv() unless the protocol you are implementing
   *    requires a specific IV value.
   * -# Call psa_cipher_update() zero, one or more times, passing a fragment
   *    of the message each time.
   * -# Call psa_cipher_finish().
   *
   * If an error occurs at any step after a call to psa_cipher_encrypt_setup(),
   * the operation will need to be reset by a call to psa_cipher_abort(). The
   * application may call psa_cipher_abort() at any time after the operation
   * has been initialized.
   *
   * After a successful call to psa_cipher_encrypt_setup(), the application must
   * eventually terminate the operation. The following events terminate an
   * operation:
   * - A successful call to psa_cipher_finish().
   * - A call to psa_cipher_abort().
   *
   * \param[in,out] operation     The operation object to set up. It must have
   *                              been initialized as per the documentation for
   *                              #psa_cipher_operation_t and not yet in use.
   * \param key                   Identifier of the key to use for the operation.
   *                              It must remain valid until the operation
   *                              terminates. It must allow the usage
   *                              #PSA_KEY_USAGE_ENCRYPT.
   * \param alg                   The cipher algorithm to compute
   *                              (\c PSA_ALG_XXX value such that
   *                              #PSA_ALG_IS_CIPHER(\p alg) is true).
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not a cipher algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be inactive).
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_cipher_encrypt_setup(psa_cipher_operation_t *operation,
                                        mbedtls_svc_key_id_t key,
                                        psa_algorithm_t alg);
  
  /** Set the key for a multipart symmetric decryption operation.
   *
   * The sequence of operations to decrypt a message with a symmetric cipher
   * is as follows:
   * -# Allocate an operation object which will be passed to all the functions
   *    listed here.
   * -# Initialize the operation object with one of the methods described in the
   *    documentation for #psa_cipher_operation_t, e.g.
   *    #PSA_CIPHER_OPERATION_INIT.
   * -# Call psa_cipher_decrypt_setup() to specify the algorithm and key.
   * -# Call psa_cipher_set_iv() with the IV (initialization vector) for the
   *    decryption. If the IV is prepended to the ciphertext, you can call
   *    psa_cipher_update() on a buffer containing the IV followed by the
   *    beginning of the message.
   * -# Call psa_cipher_update() zero, one or more times, passing a fragment
   *    of the message each time.
   * -# Call psa_cipher_finish().
   *
   * If an error occurs at any step after a call to psa_cipher_decrypt_setup(),
   * the operation will need to be reset by a call to psa_cipher_abort(). The
   * application may call psa_cipher_abort() at any time after the operation
   * has been initialized.
   *
   * After a successful call to psa_cipher_decrypt_setup(), the application must
   * eventually terminate the operation. The following events terminate an
   * operation:
   * - A successful call to psa_cipher_finish().
   * - A call to psa_cipher_abort().
   *
   * \param[in,out] operation     The operation object to set up. It must have
   *                              been initialized as per the documentation for
   *                              #psa_cipher_operation_t and not yet in use.
   * \param key                   Identifier of the key to use for the operation.
   *                              It must remain valid until the operation
   *                              terminates. It must allow the usage
   *                              #PSA_KEY_USAGE_DECRYPT.
   * \param alg                   The cipher algorithm to compute
   *                              (\c PSA_ALG_XXX value such that
   *                              #PSA_ALG_IS_CIPHER(\p alg) is true).
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not a cipher algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be inactive).
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_cipher_decrypt_setup(psa_cipher_operation_t *operation,
                                        mbedtls_svc_key_id_t key,
                                        psa_algorithm_t alg);
  
  /** Generate an IV for a symmetric encryption operation.
   *
   * This function generates a random IV (initialization vector), nonce
   * or initial counter value for the encryption operation as appropriate
   * for the chosen algorithm, key type and key size.
   *
   * The application must call psa_cipher_encrypt_setup() before
   * calling this function.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_cipher_abort().
   *
   * \param[in,out] operation     Active cipher operation.
   * \param[out] iv               Buffer where the generated IV is to be written.
   * \param iv_size               Size of the \p iv buffer in bytes.
   * \param[out] iv_length        On success, the number of bytes of the
   *                              generated IV.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active, with no IV set).
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p iv buffer is too small.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_cipher_generate_iv(psa_cipher_operation_t *operation,
                                      uint8_t *iv,
                                      size_t iv_size,
                                      size_t *iv_length);
  
  /** Set the IV for a symmetric encryption or decryption operation.
   *
   * This function sets the IV (initialization vector), nonce
   * or initial counter value for the encryption or decryption operation.
   *
   * The application must call psa_cipher_encrypt_setup() before
   * calling this function.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_cipher_abort().
   *
   * \note When encrypting, applications should use psa_cipher_generate_iv()
   * instead of this function, unless implementing a protocol that requires
   * a non-random IV.
   *
   * \param[in,out] operation     Active cipher operation.
   * \param[in] iv                Buffer containing the IV to use.
   * \param iv_length             Size of the IV in bytes.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be an active cipher
   *         encrypt operation, with no IV set).
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The size of \p iv is not acceptable for the chosen algorithm,
   *         or the chosen algorithm does not use an IV.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_cipher_set_iv(psa_cipher_operation_t *operation,
                                 const uint8_t *iv,
                                 size_t iv_length);
  
  /** Encrypt or decrypt a message fragment in an active cipher operation.
   *
   * Before calling this function, you must:
   * 1. Call either psa_cipher_encrypt_setup() or psa_cipher_decrypt_setup().
   *    The choice of setup function determines whether this function
   *    encrypts or decrypts its input.
   * 2. If the algorithm requires an IV, call psa_cipher_generate_iv()
   *    (recommended when encrypting) or psa_cipher_set_iv().
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_cipher_abort().
   *
   * \param[in,out] operation     Active cipher operation.
   * \param[in] input             Buffer containing the message fragment to
   *                              encrypt or decrypt.
   * \param input_length          Size of the \p input buffer in bytes.
   * \param[out] output           Buffer where the output is to be written.
   * \param output_size           Size of the \p output buffer in bytes.
   * \param[out] output_length    On success, the number of bytes
   *                              that make up the returned output.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active, with an IV set
   *         if required for the algorithm).
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p output buffer is too small.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_cipher_update(psa_cipher_operation_t *operation,
                                 const uint8_t *input,
                                 size_t input_length,
                                 uint8_t *output,
                                 size_t output_size,
                                 size_t *output_length);
  
  /** Finish encrypting or decrypting a message in a cipher operation.
   *
   * The application must call psa_cipher_encrypt_setup() or
   * psa_cipher_decrypt_setup() before calling this function. The choice
   * of setup function determines whether this function encrypts or
   * decrypts its input.
   *
   * This function finishes the encryption or decryption of the message
   * formed by concatenating the inputs passed to preceding calls to
   * psa_cipher_update().
   *
   * When this function returns successfuly, the operation becomes inactive.
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_cipher_abort().
   *
   * \param[in,out] operation     Active cipher operation.
   * \param[out] output           Buffer where the output is to be written.
   * \param output_size           Size of the \p output buffer in bytes.
   * \param[out] output_length    On success, the number of bytes
   *                              that make up the returned output.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The total input size passed to this operation is not valid for
   *         this particular algorithm. For example, the algorithm is a based
   *         on block cipher and requires a whole number of blocks, but the
   *         total input size is not a multiple of the block size.
   * \retval #PSA_ERROR_INVALID_PADDING
   *         This is a decryption operation for an algorithm that includes
   *         padding, and the ciphertext does not contain valid padding.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active, with an IV set
   *         if required for the algorithm).
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p output buffer is too small.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_cipher_finish(psa_cipher_operation_t *operation,
                                 uint8_t *output,
                                 size_t output_size,
                                 size_t *output_length);
  
  /** Abort a cipher operation.
   *
   * Aborting an operation frees all associated resources except for the
   * \p operation structure itself. Once aborted, the operation object
   * can be reused for another operation by calling
   * psa_cipher_encrypt_setup() or psa_cipher_decrypt_setup() again.
   *
   * You may call this function any time after the operation object has
   * been initialized as described in #psa_cipher_operation_t.
   *
   * In particular, calling psa_cipher_abort() after the operation has been
   * terminated by a call to psa_cipher_abort() or psa_cipher_finish()
   * is safe and has no effect.
   *
   * \param[in,out] operation     Initialized cipher operation.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_cipher_abort(psa_cipher_operation_t *operation);
  
  /**@}*/
  
  /** \defgroup aead Authenticated encryption with associated data (AEAD)
   * @{
   */
  
  /** Process an authenticated encryption operation.
   *
   * \param key                     Identifier of the key to use for the
   *                                operation. It must allow the usage
   *                                #PSA_KEY_USAGE_ENCRYPT.
   * \param alg                     The AEAD algorithm to compute
   *                                (\c PSA_ALG_XXX value such that
   *                                #PSA_ALG_IS_AEAD(\p alg) is true).
   * \param[in] nonce               Nonce or IV to use.
   * \param nonce_length            Size of the \p nonce buffer in bytes.
   * \param[in] additional_data     Additional data that will be authenticated
   *                                but not encrypted.
   * \param additional_data_length  Size of \p additional_data in bytes.
   * \param[in] plaintext           Data that will be authenticated and
   *                                encrypted.
   * \param plaintext_length        Size of \p plaintext in bytes.
   * \param[out] ciphertext         Output buffer for the authenticated and
   *                                encrypted data. The additional data is not
   *                                part of this output. For algorithms where the
   *                                encrypted data and the authentication tag
   *                                are defined as separate outputs, the
   *                                authentication tag is appended to the
   *                                encrypted data.
   * \param ciphertext_size         Size of the \p ciphertext buffer in bytes.
   *                                This must be appropriate for the selected
   *                                algorithm and key:
   *                                - A sufficient output size is
   *                                  #PSA_AEAD_ENCRYPT_OUTPUT_SIZE(\c key_type,
   *                                  \p alg, \p plaintext_length) where
   *                                  \c key_type is the type of \p key.
   *                                - #PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE(\p
   *                                  plaintext_length) evaluates to the maximum
   *                                  ciphertext size of any supported AEAD
   *                                  encryption.
   * \param[out] ciphertext_length  On success, the size of the output
   *                                in the \p ciphertext buffer.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not an AEAD algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         \p ciphertext_size is too small.
   *         #PSA_AEAD_ENCRYPT_OUTPUT_SIZE(\c key_type, \p alg,
   *         \p plaintext_length) or
   *         #PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE(\p plaintext_length) can be used to
   *         determine the required buffer size.
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_encrypt(mbedtls_svc_key_id_t key,
                                psa_algorithm_t alg,
                                const uint8_t *nonce,
                                size_t nonce_length,
                                const uint8_t *additional_data,
                                size_t additional_data_length,
                                const uint8_t *plaintext,
                                size_t plaintext_length,
                                uint8_t *ciphertext,
                                size_t ciphertext_size,
                                size_t *ciphertext_length);
  
  /** Process an authenticated decryption operation.
   *
   * \param key                     Identifier of the key to use for the
   *                                operation. It must allow the usage
   *                                #PSA_KEY_USAGE_DECRYPT.
   * \param alg                     The AEAD algorithm to compute
   *                                (\c PSA_ALG_XXX value such that
   *                                #PSA_ALG_IS_AEAD(\p alg) is true).
   * \param[in] nonce               Nonce or IV to use.
   * \param nonce_length            Size of the \p nonce buffer in bytes.
   * \param[in] additional_data     Additional data that has been authenticated
   *                                but not encrypted.
   * \param additional_data_length  Size of \p additional_data in bytes.
   * \param[in] ciphertext          Data that has been authenticated and
   *                                encrypted. For algorithms where the
   *                                encrypted data and the authentication tag
   *                                are defined as separate inputs, the buffer
   *                                must contain the encrypted data followed
   *                                by the authentication tag.
   * \param ciphertext_length       Size of \p ciphertext in bytes.
   * \param[out] plaintext          Output buffer for the decrypted data.
   * \param plaintext_size          Size of the \p plaintext buffer in bytes.
   *                                This must be appropriate for the selected
   *                                algorithm and key:
   *                                - A sufficient output size is
   *                                  #PSA_AEAD_DECRYPT_OUTPUT_SIZE(\c key_type,
   *                                  \p alg, \p ciphertext_length) where
   *                                  \c key_type is the type of \p key.
   *                                - #PSA_AEAD_DECRYPT_OUTPUT_MAX_SIZE(\p
   *                                  ciphertext_length) evaluates to the maximum
   *                                  plaintext size of any supported AEAD
   *                                  decryption.
   * \param[out] plaintext_length   On success, the size of the output
   *                                in the \p plaintext buffer.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_INVALID_SIGNATURE
   *         The ciphertext is not authentic.
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not an AEAD algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         \p plaintext_size is too small.
   *         #PSA_AEAD_DECRYPT_OUTPUT_SIZE(\c key_type, \p alg,
   *         \p ciphertext_length) or
   *         #PSA_AEAD_DECRYPT_OUTPUT_MAX_SIZE(\p ciphertext_length) can be used
   *         to determine the required buffer size.
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_decrypt(mbedtls_svc_key_id_t key,
                                psa_algorithm_t alg,
                                const uint8_t *nonce,
                                size_t nonce_length,
                                const uint8_t *additional_data,
                                size_t additional_data_length,
                                const uint8_t *ciphertext,
                                size_t ciphertext_length,
                                uint8_t *plaintext,
                                size_t plaintext_size,
                                size_t *plaintext_length);
  
  /** The type of the state data structure for multipart AEAD operations.
   *
   * Before calling any function on an AEAD operation object, the application
   * must initialize it by any of the following means:
   * - Set the structure to all-bits-zero, for example:
   *   \code
   *   psa_aead_operation_t operation;
   *   memset(&operation, 0, sizeof(operation));
   *   \endcode
   * - Initialize the structure to logical zero values, for example:
   *   \code
   *   psa_aead_operation_t operation = {0};
   *   \endcode
   * - Initialize the structure to the initializer #PSA_AEAD_OPERATION_INIT,
   *   for example:
   *   \code
   *   psa_aead_operation_t operation = PSA_AEAD_OPERATION_INIT;
   *   \endcode
   * - Assign the result of the function psa_aead_operation_init()
   *   to the structure, for example:
   *   \code
   *   psa_aead_operation_t operation;
   *   operation = psa_aead_operation_init();
   *   \endcode
   *
   * This is an implementation-defined \c struct. Applications should not
   * make any assumptions about the content of this structure.
   * Implementation details can change in future versions without notice. */
  typedef struct psa_aead_operation_s psa_aead_operation_t;
  
  /** \def PSA_AEAD_OPERATION_INIT
   *
   * This macro returns a suitable initializer for an AEAD operation object of
   * type #psa_aead_operation_t.
   */
  
  /** Return an initial value for an AEAD operation object.
   */
  static psa_aead_operation_t psa_aead_operation_init(void);
  
  /** Set the key for a multipart authenticated encryption operation.
   *
   * The sequence of operations to encrypt a message with authentication
   * is as follows:
   * -# Allocate an operation object which will be passed to all the functions
   *    listed here.
   * -# Initialize the operation object with one of the methods described in the
   *    documentation for #psa_aead_operation_t, e.g.
   *    #PSA_AEAD_OPERATION_INIT.
   * -# Call psa_aead_encrypt_setup() to specify the algorithm and key.
   * -# If needed, call psa_aead_set_lengths() to specify the length of the
   *    inputs to the subsequent calls to psa_aead_update_ad() and
   *    psa_aead_update(). See the documentation of psa_aead_set_lengths()
   *    for details.
   * -# Call either psa_aead_generate_nonce() or psa_aead_set_nonce() to
   *    generate or set the nonce. You should use
   *    psa_aead_generate_nonce() unless the protocol you are implementing
   *    requires a specific nonce value.
   * -# Call psa_aead_update_ad() zero, one or more times, passing a fragment
   *    of the non-encrypted additional authenticated data each time.
   * -# Call psa_aead_update() zero, one or more times, passing a fragment
   *    of the message to encrypt each time.
   * -# Call psa_aead_finish().
   *
   * If an error occurs at any step after a call to psa_aead_encrypt_setup(),
   * the operation will need to be reset by a call to psa_aead_abort(). The
   * application may call psa_aead_abort() at any time after the operation
   * has been initialized.
   *
   * After a successful call to psa_aead_encrypt_setup(), the application must
   * eventually terminate the operation. The following events terminate an
   * operation:
   * - A successful call to psa_aead_finish().
   * - A call to psa_aead_abort().
   *
   * \param[in,out] operation     The operation object to set up. It must have
   *                              been initialized as per the documentation for
   *                              #psa_aead_operation_t and not yet in use.
   * \param key                   Identifier of the key to use for the operation.
   *                              It must remain valid until the operation
   *                              terminates. It must allow the usage
   *                              #PSA_KEY_USAGE_ENCRYPT.
   * \param alg                   The AEAD algorithm to compute
   *                              (\c PSA_ALG_XXX value such that
   *                              #PSA_ALG_IS_AEAD(\p alg) is true).
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be inactive).
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not an AEAD algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_encrypt_setup(psa_aead_operation_t *operation,
                                      mbedtls_svc_key_id_t key,
                                      psa_algorithm_t alg);
  
  /** Set the key for a multipart authenticated decryption operation.
   *
   * The sequence of operations to decrypt a message with authentication
   * is as follows:
   * -# Allocate an operation object which will be passed to all the functions
   *    listed here.
   * -# Initialize the operation object with one of the methods described in the
   *    documentation for #psa_aead_operation_t, e.g.
   *    #PSA_AEAD_OPERATION_INIT.
   * -# Call psa_aead_decrypt_setup() to specify the algorithm and key.
   * -# If needed, call psa_aead_set_lengths() to specify the length of the
   *    inputs to the subsequent calls to psa_aead_update_ad() and
   *    psa_aead_update(). See the documentation of psa_aead_set_lengths()
   *    for details.
   * -# Call psa_aead_set_nonce() with the nonce for the decryption.
   * -# Call psa_aead_update_ad() zero, one or more times, passing a fragment
   *    of the non-encrypted additional authenticated data each time.
   * -# Call psa_aead_update() zero, one or more times, passing a fragment
   *    of the ciphertext to decrypt each time.
   * -# Call psa_aead_verify().
   *
   * If an error occurs at any step after a call to psa_aead_decrypt_setup(),
   * the operation will need to be reset by a call to psa_aead_abort(). The
   * application may call psa_aead_abort() at any time after the operation
   * has been initialized.
   *
   * After a successful call to psa_aead_decrypt_setup(), the application must
   * eventually terminate the operation. The following events terminate an
   * operation:
   * - A successful call to psa_aead_verify().
   * - A call to psa_aead_abort().
   *
   * \param[in,out] operation     The operation object to set up. It must have
   *                              been initialized as per the documentation for
   *                              #psa_aead_operation_t and not yet in use.
   * \param key                   Identifier of the key to use for the operation.
   *                              It must remain valid until the operation
   *                              terminates. It must allow the usage
   *                              #PSA_KEY_USAGE_DECRYPT.
   * \param alg                   The AEAD algorithm to compute
   *                              (\c PSA_ALG_XXX value such that
   *                              #PSA_ALG_IS_AEAD(\p alg) is true).
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be inactive).
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p key is not compatible with \p alg.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not supported or is not an AEAD algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_decrypt_setup(psa_aead_operation_t *operation,
                                      mbedtls_svc_key_id_t key,
                                      psa_algorithm_t alg);
  
  /** Generate a random nonce for an authenticated encryption operation.
   *
   * This function generates a random nonce for the authenticated encryption
   * operation with an appropriate size for the chosen algorithm, key type
   * and key size.
   *
   * The application must call psa_aead_encrypt_setup() before
   * calling this function.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_aead_abort().
   *
   * \param[in,out] operation     Active AEAD operation.
   * \param[out] nonce            Buffer where the generated nonce is to be
   *                              written.
   * \param nonce_size            Size of the \p nonce buffer in bytes.
   * \param[out] nonce_length     On success, the number of bytes of the
   *                              generated nonce.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be an active aead encrypt
   *         operation, with no nonce set).
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p nonce buffer is too small.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_generate_nonce(psa_aead_operation_t *operation,
                                       uint8_t *nonce,
                                       size_t nonce_size,
                                       size_t *nonce_length);
  
  /** Set the nonce for an authenticated encryption or decryption operation.
   *
   * This function sets the nonce for the authenticated
   * encryption or decryption operation.
   *
   * The application must call psa_aead_encrypt_setup() or
   * psa_aead_decrypt_setup() before calling this function.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_aead_abort().
   *
   * \note When encrypting, applications should use psa_aead_generate_nonce()
   * instead of this function, unless implementing a protocol that requires
   * a non-random IV.
   *
   * \param[in,out] operation     Active AEAD operation.
   * \param[in] nonce             Buffer containing the nonce to use.
   * \param nonce_length          Size of the nonce in bytes.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active, with no nonce
   *         set).
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The size of \p nonce is not acceptable for the chosen algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_set_nonce(psa_aead_operation_t *operation,
                                  const uint8_t *nonce,
                                  size_t nonce_length);
  
  /** Declare the lengths of the message and additional data for AEAD.
   *
   * The application must call this function before calling
   * psa_aead_update_ad() or psa_aead_update() if the algorithm for
   * the operation requires it. If the algorithm does not require it,
   * calling this function is optional, but if this function is called
   * then the implementation must enforce the lengths.
   *
   * You may call this function before or after setting the nonce with
   * psa_aead_set_nonce() or psa_aead_generate_nonce().
   *
   * - For #PSA_ALG_CCM, calling this function is required.
   * - For the other AEAD algorithms defined in this specification, calling
   *   this function is not required.
   * - For vendor-defined algorithm, refer to the vendor documentation.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_aead_abort().
   *
   * \param[in,out] operation     Active AEAD operation.
   * \param ad_length             Size of the non-encrypted additional
   *                              authenticated data in bytes.
   * \param plaintext_length      Size of the plaintext to encrypt in bytes.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active, and
   *         psa_aead_update_ad() and psa_aead_update() must not have been
   *         called yet).
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         At least one of the lengths is not acceptable for the chosen
   *         algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_set_lengths(psa_aead_operation_t *operation,
                                    size_t ad_length,
                                    size_t plaintext_length);
  
  /** Pass additional data to an active AEAD operation.
   *
   * Additional data is authenticated, but not encrypted.
   *
   * You may call this function multiple times to pass successive fragments
   * of the additional data. You may not call this function after passing
   * data to encrypt or decrypt with psa_aead_update().
   *
   * Before calling this function, you must:
   * 1. Call either psa_aead_encrypt_setup() or psa_aead_decrypt_setup().
   * 2. Set the nonce with psa_aead_generate_nonce() or psa_aead_set_nonce().
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_aead_abort().
   *
   * \warning When decrypting, until psa_aead_verify() has returned #PSA_SUCCESS,
   *          there is no guarantee that the input is valid. Therefore, until
   *          you have called psa_aead_verify() and it has returned #PSA_SUCCESS,
   *          treat the input as untrusted and prepare to undo any action that
   *          depends on the input if psa_aead_verify() returns an error status.
   *
   * \param[in,out] operation     Active AEAD operation.
   * \param[in] input             Buffer containing the fragment of
   *                              additional data.
   * \param input_length          Size of the \p input buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active, have a nonce
   *         set, have lengths set if required by the algorithm, and
   *         psa_aead_update() must not have been called yet).
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The total input length overflows the additional data length that
   *         was previously specified with psa_aead_set_lengths().
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_update_ad(psa_aead_operation_t *operation,
                                  const uint8_t *input,
                                  size_t input_length);
  
  /** Encrypt or decrypt a message fragment in an active AEAD operation.
   *
   * Before calling this function, you must:
   * 1. Call either psa_aead_encrypt_setup() or psa_aead_decrypt_setup().
   *    The choice of setup function determines whether this function
   *    encrypts or decrypts its input.
   * 2. Set the nonce with psa_aead_generate_nonce() or psa_aead_set_nonce().
   * 3. Call psa_aead_update_ad() to pass all the additional data.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_aead_abort().
   *
   * \warning When decrypting, until psa_aead_verify() has returned #PSA_SUCCESS,
   *          there is no guarantee that the input is valid. Therefore, until
   *          you have called psa_aead_verify() and it has returned #PSA_SUCCESS:
   *          - Do not use the output in any way other than storing it in a
   *            confidential location. If you take any action that depends
   *            on the tentative decrypted data, this action will need to be
   *            undone if the input turns out not to be valid. Furthermore,
   *            if an adversary can observe that this action took place
   *            (for example through timing), they may be able to use this
   *            fact as an oracle to decrypt any message encrypted with the
   *            same key.
   *          - In particular, do not copy the output anywhere but to a
   *            memory or storage space that you have exclusive access to.
   *
   * This function does not require the input to be aligned to any
   * particular block boundary. If the implementation can only process
   * a whole block at a time, it must consume all the input provided, but
   * it may delay the end of the corresponding output until a subsequent
   * call to psa_aead_update(), psa_aead_finish() or psa_aead_verify()
   * provides sufficient input. The amount of data that can be delayed
   * in this way is bounded by #PSA_AEAD_UPDATE_OUTPUT_SIZE.
   *
   * \param[in,out] operation     Active AEAD operation.
   * \param[in] input             Buffer containing the message fragment to
   *                              encrypt or decrypt.
   * \param input_length          Size of the \p input buffer in bytes.
   * \param[out] output           Buffer where the output is to be written.
   * \param output_size           Size of the \p output buffer in bytes.
   *                              This must be appropriate for the selected
   *                                algorithm and key:
   *                                - A sufficient output size is
   *                                  #PSA_AEAD_UPDATE_OUTPUT_SIZE(\c key_type,
   *                                  \c alg, \p input_length) where
   *                                  \c key_type is the type of key and \c alg is
   *                                  the algorithm that were used to set up the
   *                                  operation.
   *                                - #PSA_AEAD_UPDATE_OUTPUT_MAX_SIZE(\p
   *                                  input_length) evaluates to the maximum
   *                                  output size of any supported AEAD
   *                                  algorithm.
   * \param[out] output_length    On success, the number of bytes
   *                              that make up the returned output.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active, have a nonce
   *         set, and have lengths set if required by the algorithm).
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p output buffer is too small.
   *         #PSA_AEAD_UPDATE_OUTPUT_SIZE(\c key_type, \c alg, \p input_length) or
   *         #PSA_AEAD_UPDATE_OUTPUT_MAX_SIZE(\p input_length) can be used to
   *         determine the required buffer size.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The total length of input to psa_aead_update_ad() so far is
   *         less than the additional data length that was previously
   *         specified with psa_aead_set_lengths().
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The total input length overflows the plaintext length that
   *         was previously specified with psa_aead_set_lengths().
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_update(psa_aead_operation_t *operation,
                               const uint8_t *input,
                               size_t input_length,
                               uint8_t *output,
                               size_t output_size,
                               size_t *output_length);
  
  /** Finish encrypting a message in an AEAD operation.
   *
   * The operation must have been set up with psa_aead_encrypt_setup().
   *
   * This function finishes the authentication of the additional data
   * formed by concatenating the inputs passed to preceding calls to
   * psa_aead_update_ad() with the plaintext formed by concatenating the
   * inputs passed to preceding calls to psa_aead_update().
   *
   * This function has two output buffers:
   * - \p ciphertext contains trailing ciphertext that was buffered from
   *   preceding calls to psa_aead_update().
   * - \p tag contains the authentication tag.
   *
   * When this function returns successfuly, the operation becomes inactive.
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_aead_abort().
   *
   * \param[in,out] operation     Active AEAD operation.
   * \param[out] ciphertext       Buffer where the last part of the ciphertext
   *                              is to be written.
   * \param ciphertext_size       Size of the \p ciphertext buffer in bytes.
   *                              This must be appropriate for the selected
   *                              algorithm and key:
   *                              - A sufficient output size is
   *                                #PSA_AEAD_FINISH_OUTPUT_SIZE(\c key_type,
   *                                \c alg) where \c key_type is the type of key
   *                                and \c alg is the algorithm that were used to
   *                                set up the operation.
   *                              - #PSA_AEAD_FINISH_OUTPUT_MAX_SIZE evaluates to
   *                                the maximum output size of any supported AEAD
   *                                algorithm.
   * \param[out] ciphertext_length On success, the number of bytes of
   *                              returned ciphertext.
   * \param[out] tag              Buffer where the authentication tag is
   *                              to be written.
   * \param tag_size              Size of the \p tag buffer in bytes.
   *                              This must be appropriate for the selected
   *                              algorithm and key:
   *                              - The exact tag size is #PSA_AEAD_TAG_LENGTH(\c
   *                                key_type, \c key_bits, \c alg) where
   *                                \c key_type and \c key_bits are the type and
   *                                bit-size of the key, and \c alg is the
   *                                algorithm that were used in the call to
   *                                psa_aead_encrypt_setup().
   *                              - #PSA_AEAD_TAG_MAX_SIZE evaluates to the
   *                                maximum tag size of any supported AEAD
   *                                algorithm.
   * \param[out] tag_length       On success, the number of bytes
   *                              that make up the returned tag.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be an active encryption
   *         operation with a nonce set).
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p ciphertext or \p tag buffer is too small.
   *         #PSA_AEAD_FINISH_OUTPUT_SIZE(\c key_type, \c alg) or
   *         #PSA_AEAD_FINISH_OUTPUT_MAX_SIZE can be used to determine the
   *         required \p ciphertext buffer size. #PSA_AEAD_TAG_LENGTH(\c key_type,
   *         \c key_bits, \c alg) or #PSA_AEAD_TAG_MAX_SIZE can be used to
   *         determine the required \p tag buffer size.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The total length of input to psa_aead_update_ad() so far is
   *         less than the additional data length that was previously
   *         specified with psa_aead_set_lengths().
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The total length of input to psa_aead_update() so far is
   *         less than the plaintext length that was previously
   *         specified with psa_aead_set_lengths().
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_finish(psa_aead_operation_t *operation,
                               uint8_t *ciphertext,
                               size_t ciphertext_size,
                               size_t *ciphertext_length,
                               uint8_t *tag,
                               size_t tag_size,
                               size_t *tag_length);
  
  /** Finish authenticating and decrypting a message in an AEAD operation.
   *
   * The operation must have been set up with psa_aead_decrypt_setup().
   *
   * This function finishes the authenticated decryption of the message
   * components:
   *
   * -  The additional data consisting of the concatenation of the inputs
   *    passed to preceding calls to psa_aead_update_ad().
   * -  The ciphertext consisting of the concatenation of the inputs passed to
   *    preceding calls to psa_aead_update().
   * -  The tag passed to this function call.
   *
   * If the authentication tag is correct, this function outputs any remaining
   * plaintext and reports success. If the authentication tag is not correct,
   * this function returns #PSA_ERROR_INVALID_SIGNATURE.
   *
   * When this function returns successfuly, the operation becomes inactive.
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_aead_abort().
   *
   * \note Implementations shall make the best effort to ensure that the
   * comparison between the actual tag and the expected tag is performed
   * in constant time.
   *
   * \param[in,out] operation     Active AEAD operation.
   * \param[out] plaintext        Buffer where the last part of the plaintext
   *                              is to be written. This is the remaining data
   *                              from previous calls to psa_aead_update()
   *                              that could not be processed until the end
   *                              of the input.
   * \param plaintext_size        Size of the \p plaintext buffer in bytes.
   *                              This must be appropriate for the selected algorithm and key:
   *                              - A sufficient output size is
   *                                #PSA_AEAD_VERIFY_OUTPUT_SIZE(\c key_type,
   *                                \c alg) where \c key_type is the type of key
   *                                and \c alg is the algorithm that were used to
   *                                set up the operation.
   *                              - #PSA_AEAD_VERIFY_OUTPUT_MAX_SIZE evaluates to
   *                                the maximum output size of any supported AEAD
   *                                algorithm.
   * \param[out] plaintext_length On success, the number of bytes of
   *                              returned plaintext.
   * \param[in] tag               Buffer containing the authentication tag.
   * \param tag_length            Size of the \p tag buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_SIGNATURE
   *         The calculations were successful, but the authentication tag is
   *         not correct.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be an active decryption
   *         operation with a nonce set).
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p plaintext buffer is too small.
   *         #PSA_AEAD_VERIFY_OUTPUT_SIZE(\c key_type, \c alg) or
   *         #PSA_AEAD_VERIFY_OUTPUT_MAX_SIZE can be used to determine the
   *         required buffer size.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The total length of input to psa_aead_update_ad() so far is
   *         less than the additional data length that was previously
   *         specified with psa_aead_set_lengths().
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The total length of input to psa_aead_update() so far is
   *         less than the plaintext length that was previously
   *         specified with psa_aead_set_lengths().
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_verify(psa_aead_operation_t *operation,
                               uint8_t *plaintext,
                               size_t plaintext_size,
                               size_t *plaintext_length,
                               const uint8_t *tag,
                               size_t tag_length);
  
  /** Abort an AEAD operation.
   *
   * Aborting an operation frees all associated resources except for the
   * \p operation structure itself. Once aborted, the operation object
   * can be reused for another operation by calling
   * psa_aead_encrypt_setup() or psa_aead_decrypt_setup() again.
   *
   * You may call this function any time after the operation object has
   * been initialized as described in #psa_aead_operation_t.
   *
   * In particular, calling psa_aead_abort() after the operation has been
   * terminated by a call to psa_aead_abort(), psa_aead_finish() or
   * psa_aead_verify() is safe and has no effect.
   *
   * \param[in,out] operation     Initialized AEAD operation.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_aead_abort(psa_aead_operation_t *operation);
  
  /**@}*/
  
  /** \defgroup asymmetric Asymmetric cryptography
   * @{
   */
  
  /**
   * \brief Sign a message with a private key. For hash-and-sign algorithms,
   *        this includes the hashing step.
   *
   * \note To perform a multi-part hash-and-sign signature algorithm, first use
   *       a multi-part hash operation and then pass the resulting hash to
   *       psa_sign_hash(). PSA_ALG_GET_HASH(\p alg) can be used to determine the
   *       hash algorithm to use.
   *
   * \param[in]  key              Identifier of the key to use for the operation.
   *                              It must be an asymmetric key pair. The key must
   *                              allow the usage #PSA_KEY_USAGE_SIGN_MESSAGE.
   * \param[in]  alg              An asymmetric signature algorithm (PSA_ALG_XXX
   *                              value such that #PSA_ALG_IS_SIGN_MESSAGE(\p alg)
   *                              is true), that is compatible with the type of
   *                              \p key.
   * \param[in]  input            The input message to sign.
   * \param[in]  input_length     Size of the \p input buffer in bytes.
   * \param[out] signature        Buffer where the signature is to be written.
   * \param[in]  signature_size   Size of the \p signature buffer in bytes. This
   *                              must be appropriate for the selected
   *                              algorithm and key:
   *                              - The required signature size is
   *                                #PSA_SIGN_OUTPUT_SIZE(\c key_type, \c key_bits, \p alg)
   *                                where \c key_type and \c key_bits are the type and
   *                                bit-size respectively of key.
   *                              - #PSA_SIGNATURE_MAX_SIZE evaluates to the
   *                                maximum signature size of any supported
   *                                signature algorithm.
   * \param[out] signature_length On success, the number of bytes that make up
   *                              the returned signature value.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         The key does not have the #PSA_KEY_USAGE_SIGN_MESSAGE flag,
   *         or it does not permit the requested algorithm.
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p signature buffer is too small. You can
   *         determine a sufficient buffer size by calling
   *         #PSA_SIGN_OUTPUT_SIZE(\c key_type, \c key_bits, \p alg)
   *         where \c key_type and \c key_bits are the type and bit-size
   *         respectively of \p key.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_DATA_CORRUPT
   * \retval #PSA_ERROR_DATA_INVALID
   * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_sign_message( mbedtls_svc_key_id_t key,
                                 psa_algorithm_t alg,
                                 const uint8_t * input,
                                 size_t input_length,
                                 uint8_t * signature,
                                 size_t signature_size,
                                 size_t * signature_length );
  
  /** \brief Verify the signature of a message with a public key, using
   *         a hash-and-sign verification algorithm.
   *
   * \note To perform a multi-part hash-and-sign signature verification
   *       algorithm, first use a multi-part hash operation to hash the message
   *       and then pass the resulting hash to psa_verify_hash().
   *       PSA_ALG_GET_HASH(\p alg) can be used to determine the hash algorithm
   *       to use.
   *
   * \param[in]  key              Identifier of the key to use for the operation.
   *                              It must be a public key or an asymmetric key
   *                              pair. The key must allow the usage
   *                              #PSA_KEY_USAGE_VERIFY_MESSAGE.
   * \param[in]  alg              An asymmetric signature algorithm (PSA_ALG_XXX
   *                              value such that #PSA_ALG_IS_SIGN_MESSAGE(\p alg)
   *                              is true), that is compatible with the type of
   *                              \p key.
   * \param[in]  input            The message whose signature is to be verified.
   * \param[in]  input_length     Size of the \p input buffer in bytes.
   * \param[out] signature        Buffer containing the signature to verify.
   * \param[in]  signature_length Size of the \p signature buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         The key does not have the #PSA_KEY_USAGE_SIGN_MESSAGE flag,
   *         or it does not permit the requested algorithm.
   * \retval #PSA_ERROR_INVALID_SIGNATURE
   *         The calculation was performed successfully, but the passed signature
   *         is not a valid signature.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_DATA_CORRUPT
   * \retval #PSA_ERROR_DATA_INVALID
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_verify_message( mbedtls_svc_key_id_t key,
                                   psa_algorithm_t alg,
                                   const uint8_t * input,
                                   size_t input_length,
                                   const uint8_t * signature,
                                   size_t signature_length );
  
  /**
   * \brief Sign a hash or short message with a private key.
   *
   * Note that to perform a hash-and-sign signature algorithm, you must
   * first calculate the hash by calling psa_hash_setup(), psa_hash_update()
   * and psa_hash_finish(), or alternatively by calling psa_hash_compute().
   * Then pass the resulting hash as the \p hash
   * parameter to this function. You can use #PSA_ALG_SIGN_GET_HASH(\p alg)
   * to determine the hash algorithm to use.
   *
   * \param key                   Identifier of the key to use for the operation.
   *                              It must be an asymmetric key pair. The key must
   *                              allow the usage #PSA_KEY_USAGE_SIGN_HASH.
   * \param alg                   A signature algorithm that is compatible with
   *                              the type of \p key.
   * \param[in] hash              The hash or message to sign.
   * \param hash_length           Size of the \p hash buffer in bytes.
   * \param[out] signature        Buffer where the signature is to be written.
   * \param signature_size        Size of the \p signature buffer in bytes.
   * \param[out] signature_length On success, the number of bytes
   *                              that make up the returned signature value.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p signature buffer is too small. You can
   *         determine a sufficient buffer size by calling
   *         #PSA_SIGN_OUTPUT_SIZE(\c key_type, \c key_bits, \p alg)
   *         where \c key_type and \c key_bits are the type and bit-size
   *         respectively of \p key.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_sign_hash(mbedtls_svc_key_id_t key,
                             psa_algorithm_t alg,
                             const uint8_t *hash,
                             size_t hash_length,
                             uint8_t *signature,
                             size_t signature_size,
                             size_t *signature_length);
  
  /**
   * \brief Verify the signature of a hash or short message using a public key.
   *
   * Note that to perform a hash-and-sign signature algorithm, you must
   * first calculate the hash by calling psa_hash_setup(), psa_hash_update()
   * and psa_hash_finish(), or alternatively by calling psa_hash_compute().
   * Then pass the resulting hash as the \p hash
   * parameter to this function. You can use #PSA_ALG_SIGN_GET_HASH(\p alg)
   * to determine the hash algorithm to use.
   *
   * \param key               Identifier of the key to use for the operation. It
   *                          must be a public key or an asymmetric key pair. The
   *                          key must allow the usage
   *                          #PSA_KEY_USAGE_VERIFY_HASH.
   * \param alg               A signature algorithm that is compatible with
   *                          the type of \p key.
   * \param[in] hash          The hash or message whose signature is to be
   *                          verified.
   * \param hash_length       Size of the \p hash buffer in bytes.
   * \param[in] signature     Buffer containing the signature to verify.
   * \param signature_length  Size of the \p signature buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         The signature is valid.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_SIGNATURE
   *         The calculation was perfomed successfully, but the passed
   *         signature is not a valid signature.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_verify_hash(mbedtls_svc_key_id_t key,
                               psa_algorithm_t alg,
                               const uint8_t *hash,
                               size_t hash_length,
                               const uint8_t *signature,
                               size_t signature_length);
  
  /**
   * \brief Encrypt a short message with a public key.
   *
   * \param key                   Identifer of the key to use for the operation.
   *                              It must be a public key or an asymmetric key
   *                              pair. It must allow the usage
   *                              #PSA_KEY_USAGE_ENCRYPT.
   * \param alg                   An asymmetric encryption algorithm that is
   *                              compatible with the type of \p key.
   * \param[in] input             The message to encrypt.
   * \param input_length          Size of the \p input buffer in bytes.
   * \param[in] salt              A salt or label, if supported by the
   *                              encryption algorithm.
   *                              If the algorithm does not support a
   *                              salt, pass \c NULL.
   *                              If the algorithm supports an optional
   *                              salt and you do not want to pass a salt,
   *                              pass \c NULL.
   *
   *                              - For #PSA_ALG_RSA_PKCS1V15_CRYPT, no salt is
   *                                supported.
   * \param salt_length           Size of the \p salt buffer in bytes.
   *                              If \p salt is \c NULL, pass 0.
   * \param[out] output           Buffer where the encrypted message is to
   *                              be written.
   * \param output_size           Size of the \p output buffer in bytes.
   * \param[out] output_length    On success, the number of bytes
   *                              that make up the returned output.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p output buffer is too small. You can
   *         determine a sufficient buffer size by calling
   *         #PSA_ASYMMETRIC_ENCRYPT_OUTPUT_SIZE(\c key_type, \c key_bits, \p alg)
   *         where \c key_type and \c key_bits are the type and bit-size
   *         respectively of \p key.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_asymmetric_encrypt(mbedtls_svc_key_id_t key,
                                      psa_algorithm_t alg,
                                      const uint8_t *input,
                                      size_t input_length,
                                      const uint8_t *salt,
                                      size_t salt_length,
                                      uint8_t *output,
                                      size_t output_size,
                                      size_t *output_length);
  
  /**
   * \brief Decrypt a short message with a private key.
   *
   * \param key                   Identifier of the key to use for the operation.
   *                              It must be an asymmetric key pair. It must
   *                              allow the usage #PSA_KEY_USAGE_DECRYPT.
   * \param alg                   An asymmetric encryption algorithm that is
   *                              compatible with the type of \p key.
   * \param[in] input             The message to decrypt.
   * \param input_length          Size of the \p input buffer in bytes.
   * \param[in] salt              A salt or label, if supported by the
   *                              encryption algorithm.
   *                              If the algorithm does not support a
   *                              salt, pass \c NULL.
   *                              If the algorithm supports an optional
   *                              salt and you do not want to pass a salt,
   *                              pass \c NULL.
   *
   *                              - For #PSA_ALG_RSA_PKCS1V15_CRYPT, no salt is
   *                                supported.
   * \param salt_length           Size of the \p salt buffer in bytes.
   *                              If \p salt is \c NULL, pass 0.
   * \param[out] output           Buffer where the decrypted message is to
   *                              be written.
   * \param output_size           Size of the \c output buffer in bytes.
   * \param[out] output_length    On success, the number of bytes
   *                              that make up the returned output.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         The size of the \p output buffer is too small. You can
   *         determine a sufficient buffer size by calling
   *         #PSA_ASYMMETRIC_DECRYPT_OUTPUT_SIZE(\c key_type, \c key_bits, \p alg)
   *         where \c key_type and \c key_bits are the type and bit-size
   *         respectively of \p key.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
   * \retval #PSA_ERROR_INVALID_PADDING
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_asymmetric_decrypt(mbedtls_svc_key_id_t key,
                                      psa_algorithm_t alg,
                                      const uint8_t *input,
                                      size_t input_length,
                                      const uint8_t *salt,
                                      size_t salt_length,
                                      uint8_t *output,
                                      size_t output_size,
                                      size_t *output_length);
  
  /**@}*/
  
  /** \defgroup key_derivation Key derivation and pseudorandom generation
   * @{
   */
  
  /** The type of the state data structure for key derivation operations.
   *
   * Before calling any function on a key derivation operation object, the
   * application must initialize it by any of the following means:
   * - Set the structure to all-bits-zero, for example:
   *   \code
   *   psa_key_derivation_operation_t operation;
   *   memset(&operation, 0, sizeof(operation));
   *   \endcode
   * - Initialize the structure to logical zero values, for example:
   *   \code
   *   psa_key_derivation_operation_t operation = {0};
   *   \endcode
   * - Initialize the structure to the initializer #PSA_KEY_DERIVATION_OPERATION_INIT,
   *   for example:
   *   \code
   *   psa_key_derivation_operation_t operation = PSA_KEY_DERIVATION_OPERATION_INIT;
   *   \endcode
   * - Assign the result of the function psa_key_derivation_operation_init()
   *   to the structure, for example:
   *   \code
   *   psa_key_derivation_operation_t operation;
   *   operation = psa_key_derivation_operation_init();
   *   \endcode
   *
   * This is an implementation-defined \c struct. Applications should not
   * make any assumptions about the content of this structure.
   * Implementation details can change in future versions without notice.
   */
  typedef struct psa_key_derivation_s psa_key_derivation_operation_t;
  
  /** \def PSA_KEY_DERIVATION_OPERATION_INIT
   *
   * This macro returns a suitable initializer for a key derivation operation
   * object of type #psa_key_derivation_operation_t.
   */
  
  /** Return an initial value for a key derivation operation object.
   */
  static psa_key_derivation_operation_t psa_key_derivation_operation_init(void);
  
  /** Set up a key derivation operation.
   *
   * A key derivation algorithm takes some inputs and uses them to generate
   * a byte stream in a deterministic way.
   * This byte stream can be used to produce keys and other
   * cryptographic material.
   *
   * To derive a key:
   * -# Start with an initialized object of type #psa_key_derivation_operation_t.
   * -# Call psa_key_derivation_setup() to select the algorithm.
   * -# Provide the inputs for the key derivation by calling
   *    psa_key_derivation_input_bytes() or psa_key_derivation_input_key()
   *    as appropriate. Which inputs are needed, in what order, and whether
   *    they may be keys and if so of what type depends on the algorithm.
   * -# Optionally set the operation's maximum capacity with
   *    psa_key_derivation_set_capacity(). You may do this before, in the middle
   *    of or after providing inputs. For some algorithms, this step is mandatory
   *    because the output depends on the maximum capacity.
   * -# To derive a key, call psa_key_derivation_output_key().
   *    To derive a byte string for a different purpose, call
   *    psa_key_derivation_output_bytes().
   *    Successive calls to these functions use successive output bytes
   *    calculated by the key derivation algorithm.
   * -# Clean up the key derivation operation object with
   *    psa_key_derivation_abort().
   *
   * If this function returns an error, the key derivation operation object is
   * not changed.
   *
   * If an error occurs at any step after a call to psa_key_derivation_setup(),
   * the operation will need to be reset by a call to psa_key_derivation_abort().
   *
   * Implementations must reject an attempt to derive a key of size 0.
   *
   * \param[in,out] operation       The key derivation operation object
   *                                to set up. It must
   *                                have been initialized but not set up yet.
   * \param alg                     The key derivation algorithm to compute
   *                                (\c PSA_ALG_XXX value such that
   *                                #PSA_ALG_IS_KEY_DERIVATION(\p alg) is true).
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \c alg is not a key derivation algorithm.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \c alg is not supported or is not a key derivation algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be inactive).
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_setup(
      psa_key_derivation_operation_t *operation,
      psa_algorithm_t alg);
  
  /** Retrieve the current capacity of a key derivation operation.
   *
   * The capacity of a key derivation is the maximum number of bytes that it can
   * return. When you get *N* bytes of output from a key derivation operation,
   * this reduces its capacity by *N*.
   *
   * \param[in] operation     The operation to query.
   * \param[out] capacity     On success, the capacity of the operation.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active).
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_get_capacity(
      const psa_key_derivation_operation_t *operation,
      size_t *capacity);
  
  /** Set the maximum capacity of a key derivation operation.
   *
   * The capacity of a key derivation operation is the maximum number of bytes
   * that the key derivation operation can return from this point onwards.
   *
   * \param[in,out] operation The key derivation operation object to modify.
   * \param capacity          The new capacity of the operation.
   *                          It must be less or equal to the operation's
   *                          current capacity.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p capacity is larger than the operation's current capacity.
   *         In this case, the operation object remains valid and its capacity
   *         remains unchanged.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active).
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_set_capacity(
      psa_key_derivation_operation_t *operation,
      size_t capacity);
  
  /** Use the maximum possible capacity for a key derivation operation.
   *
   * Use this value as the capacity argument when setting up a key derivation
   * to indicate that the operation should have the maximum possible capacity.
   * The value of the maximum possible capacity depends on the key derivation
   * algorithm.
   */
  #define PSA_KEY_DERIVATION_UNLIMITED_CAPACITY ((size_t)(-1))
  
  /** Provide an input for key derivation or key agreement.
   *
   * Which inputs are required and in what order depends on the algorithm.
   * Refer to the documentation of each key derivation or key agreement
   * algorithm for information.
   *
   * This function passes direct inputs, which is usually correct for
   * non-secret inputs. To pass a secret input, which should be in a key
   * object, call psa_key_derivation_input_key() instead of this function.
   * Refer to the documentation of individual step types
   * (`PSA_KEY_DERIVATION_INPUT_xxx` values of type ::psa_key_derivation_step_t)
   * for more information.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_key_derivation_abort().
   *
   * \param[in,out] operation       The key derivation operation object to use.
   *                                It must have been set up with
   *                                psa_key_derivation_setup() and must not
   *                                have produced any output yet.
   * \param step                    Which step the input data is for.
   * \param[in] data                Input data to use.
   * \param data_length             Size of the \p data buffer in bytes.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \c step is not compatible with the operation's algorithm.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \c step does not allow direct inputs.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid for this input \p step.
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_input_bytes(
      psa_key_derivation_operation_t *operation,
      psa_key_derivation_step_t step,
      const uint8_t *data,
      size_t data_length);
  
  /** Provide a numeric input for key derivation or key agreement.
   *
   * Which inputs are required and in what order depends on the algorithm.
   * However, when an algorithm requires a particular order, numeric inputs
   * usually come first as they tend to be configuration parameters.
   * Refer to the documentation of each key derivation or key agreement
   * algorithm for information.
   *
   * This function is used for inputs which are fixed-size non-negative
   * integers.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_key_derivation_abort().
   *
   * \param[in,out] operation       The key derivation operation object to use.
   *                                It must have been set up with
   *                                psa_key_derivation_setup() and must not
   *                                have produced any output yet.
   * \param step                    Which step the input data is for.
   * \param[in] value               The value of the numeric input.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \c step is not compatible with the operation's algorithm.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \c step does not allow numeric inputs.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid for this input \p step.
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_input_integer(
      psa_key_derivation_operation_t *operation,
      psa_key_derivation_step_t step,
      uint64_t value);
  
  /** Provide an input for key derivation in the form of a key.
   *
   * Which inputs are required and in what order depends on the algorithm.
   * Refer to the documentation of each key derivation or key agreement
   * algorithm for information.
   *
   * This function obtains input from a key object, which is usually correct for
   * secret inputs or for non-secret personalization strings kept in the key
   * store. To pass a non-secret parameter which is not in the key store,
   * call psa_key_derivation_input_bytes() instead of this function.
   * Refer to the documentation of individual step types
   * (`PSA_KEY_DERIVATION_INPUT_xxx` values of type ::psa_key_derivation_step_t)
   * for more information.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_key_derivation_abort().
   *
   * \param[in,out] operation       The key derivation operation object to use.
   *                                It must have been set up with
   *                                psa_key_derivation_setup() and must not
   *                                have produced any output yet.
   * \param step                    Which step the input data is for.
   * \param key                     Identifier of the key. It must have an
   *                                appropriate type for step and must allow the
   *                                usage #PSA_KEY_USAGE_DERIVE or
   *                                #PSA_KEY_USAGE_VERIFY_DERIVATION (see note)
   *                                and the algorithm used by the operation.
   *
   * \note Once all inputs steps are completed, the operations will allow:
   * - psa_key_derivation_output_bytes() if each input was either a direct input
   *   or  a key with #PSA_KEY_USAGE_DERIVE set;
   * - psa_key_derivation_output_key() if the input for step
   *   #PSA_KEY_DERIVATION_INPUT_SECRET or #PSA_KEY_DERIVATION_INPUT_PASSWORD
   *   was from a key slot with #PSA_KEY_USAGE_DERIVE and each other input was
   *   either a direct input or a key with #PSA_KEY_USAGE_DERIVE set;
   * - psa_key_derivation_verify_bytes() if each input was either a direct input
   *   or  a key with #PSA_KEY_USAGE_VERIFY_DERIVATION set;
   * - psa_key_derivation_verify_key() under the same conditions as
   *   psa_key_derivation_verify_bytes().
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         The key allows neither #PSA_KEY_USAGE_DERIVE nor
   *         #PSA_KEY_USAGE_VERIFY_DERIVATION, or it doesn't allow this
   *         algorithm.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \c step is not compatible with the operation's algorithm.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \c step does not allow key inputs of the given type
   *         or does not allow key inputs at all.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid for this input \p step.
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_input_key(
      psa_key_derivation_operation_t *operation,
      psa_key_derivation_step_t step,
      mbedtls_svc_key_id_t key);
  
  /** Perform a key agreement and use the shared secret as input to a key
   * derivation.
   *
   * A key agreement algorithm takes two inputs: a private key \p private_key
   * a public key \p peer_key.
   * The result of this function is passed as input to a key derivation.
   * The output of this key derivation can be extracted by reading from the
   * resulting operation to produce keys and other cryptographic material.
   *
   * If this function returns an error status, the operation enters an error
   * state and must be aborted by calling psa_key_derivation_abort().
   *
   * \param[in,out] operation       The key derivation operation object to use.
   *                                It must have been set up with
   *                                psa_key_derivation_setup() with a
   *                                key agreement and derivation algorithm
   *                                \c alg (\c PSA_ALG_XXX value such that
   *                                #PSA_ALG_IS_KEY_AGREEMENT(\c alg) is true
   *                                and #PSA_ALG_IS_RAW_KEY_AGREEMENT(\c alg)
   *                                is false).
   *                                The operation must be ready for an
   *                                input of the type given by \p step.
   * \param step                    Which step the input data is for.
   * \param private_key             Identifier of the private key to use. It must
   *                                allow the usage #PSA_KEY_USAGE_DERIVE.
   * \param[in] peer_key      Public key of the peer. The peer key must be in the
   *                          same format that psa_import_key() accepts for the
   *                          public key type corresponding to the type of
   *                          private_key. That is, this function performs the
   *                          equivalent of
   *                          #psa_import_key(...,
   *                          `peer_key`, `peer_key_length`) where
   *                          with key attributes indicating the public key
   *                          type corresponding to the type of `private_key`.
   *                          For example, for EC keys, this means that peer_key
   *                          is interpreted as a point on the curve that the
   *                          private key is on. The standard formats for public
   *                          keys are documented in the documentation of
   *                          psa_export_public_key().
   * \param peer_key_length         Size of \p peer_key in bytes.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid for this key agreement \p step.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \c private_key is not compatible with \c alg,
   *         or \p peer_key is not valid for \c alg or not compatible with
   *         \c private_key.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \c alg is not supported or is not a key derivation algorithm.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \c step does not allow an input resulting from a key agreement.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_key_agreement(
      psa_key_derivation_operation_t *operation,
      psa_key_derivation_step_t step,
      mbedtls_svc_key_id_t private_key,
      const uint8_t *peer_key,
      size_t peer_key_length);
  
  /** Read some data from a key derivation operation.
   *
   * This function calculates output bytes from a key derivation algorithm and
   * return those bytes.
   * If you view the key derivation's output as a stream of bytes, this
   * function destructively reads the requested number of bytes from the
   * stream.
   * The operation's capacity decreases by the number of bytes read.
   *
   * If this function returns an error status other than
   * #PSA_ERROR_INSUFFICIENT_DATA, the operation enters an error
   * state and must be aborted by calling psa_key_derivation_abort().
   *
   * \param[in,out] operation The key derivation operation object to read from.
   * \param[out] output       Buffer where the output will be written.
   * \param output_length     Number of bytes to output.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         One of the inputs was a key whose policy didn't allow
   *         #PSA_KEY_USAGE_DERIVE.
   * \retval #PSA_ERROR_INSUFFICIENT_DATA
   *                          The operation's capacity was less than
   *                          \p output_length bytes. Note that in this case,
   *                          no output is written to the output buffer.
   *                          The operation's capacity is set to 0, thus
   *                          subsequent calls to this function will not
   *                          succeed, even with a smaller output buffer.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active and completed
   *         all required input steps).
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_output_bytes(
      psa_key_derivation_operation_t *operation,
      uint8_t *output,
      size_t output_length);
  
  /** Derive a key from an ongoing key derivation operation.
   *
   * This function calculates output bytes from a key derivation algorithm
   * and uses those bytes to generate a key deterministically.
   * The key's location, usage policy, type and size are taken from
   * \p attributes.
   *
   * If you view the key derivation's output as a stream of bytes, this
   * function destructively reads as many bytes as required from the
   * stream.
   * The operation's capacity decreases by the number of bytes read.
   *
   * If this function returns an error status other than
   * #PSA_ERROR_INSUFFICIENT_DATA, the operation enters an error
   * state and must be aborted by calling psa_key_derivation_abort().
   *
   * How much output is produced and consumed from the operation, and how
   * the key is derived, depends on the key type and on the key size
   * (denoted \c bits below):
   *
   * - For key types for which the key is an arbitrary sequence of bytes
   *   of a given size, this function is functionally equivalent to
   *   calling #psa_key_derivation_output_bytes
   *   and passing the resulting output to #psa_import_key.
   *   However, this function has a security benefit:
   *   if the implementation provides an isolation boundary then
   *   the key material is not exposed outside the isolation boundary.
   *   As a consequence, for these key types, this function always consumes
   *   exactly (\c bits / 8) bytes from the operation.
   *   The following key types defined in this specification follow this scheme:
   *
   *     - #PSA_KEY_TYPE_AES;
   *     - #PSA_KEY_TYPE_CAMELLIA;
   *     - #PSA_KEY_TYPE_DERIVE;
   *     - #PSA_KEY_TYPE_HMAC;
   *     - #PSA_KEY_TYPE_PASSWORD_HASH.
   *
   * - For ECC keys on a Montgomery elliptic curve
   *   (#PSA_KEY_TYPE_ECC_KEY_PAIR(\c curve) where \c curve designates a
   *   Montgomery curve), this function always draws a byte string whose
   *   length is determined by the curve, and sets the mandatory bits
   *   accordingly. That is:
   *
   *     - Curve25519 (#PSA_ECC_FAMILY_MONTGOMERY, 255 bits): draw a 32-byte
   *       string and process it as specified in RFC 7748 &sect;5.
   *     - Curve448 (#PSA_ECC_FAMILY_MONTGOMERY, 448 bits): draw a 56-byte
   *       string and process it as specified in RFC 7748 &sect;5.
   *
   * - For key types for which the key is represented by a single sequence of
   *   \c bits bits with constraints as to which bit sequences are acceptable,
   *   this function draws a byte string of length (\c bits / 8) bytes rounded
   *   up to the nearest whole number of bytes. If the resulting byte string
   *   is acceptable, it becomes the key, otherwise the drawn bytes are discarded.
   *   This process is repeated until an acceptable byte string is drawn.
   *   The byte string drawn from the operation is interpreted as specified
   *   for the output produced by psa_export_key().
   *   The following key types defined in this specification follow this scheme:
   *
   *     - #PSA_KEY_TYPE_DES.
   *       Force-set the parity bits, but discard forbidden weak keys.
   *       For 2-key and 3-key triple-DES, the three keys are generated
   *       successively (for example, for 3-key triple-DES,
   *       if the first 8 bytes specify a weak key and the next 8 bytes do not,
   *       discard the first 8 bytes, use the next 8 bytes as the first key,
   *       and continue reading output from the operation to derive the other
   *       two keys).
   *     - Finite-field Diffie-Hellman keys (#PSA_KEY_TYPE_DH_KEY_PAIR(\c group)
   *       where \c group designates any Diffie-Hellman group) and
   *       ECC keys on a Weierstrass elliptic curve
   *       (#PSA_KEY_TYPE_ECC_KEY_PAIR(\c curve) where \c curve designates a
   *       Weierstrass curve).
   *       For these key types, interpret the byte string as integer
   *       in big-endian order. Discard it if it is not in the range
   *       [0, *N* - 2] where *N* is the boundary of the private key domain
   *       (the prime *p* for Diffie-Hellman, the subprime *q* for DSA,
   *       or the order of the curve's base point for ECC).
   *       Add 1 to the resulting integer and use this as the private key *x*.
   *       This method allows compliance to NIST standards, specifically
   *       the methods titled "key-pair generation by testing candidates"
   *       in NIST SP 800-56A &sect;5.6.1.1.4 for Diffie-Hellman,
   *       in FIPS 186-4 &sect;B.1.2 for DSA, and
   *       in NIST SP 800-56A &sect;5.6.1.2.2 or
   *       FIPS 186-4 &sect;B.4.2 for elliptic curve keys.
   *
   * - For other key types, including #PSA_KEY_TYPE_RSA_KEY_PAIR,
   *   the way in which the operation output is consumed is
   *   implementation-defined.
   *
   * In all cases, the data that is read is discarded from the operation.
   * The operation's capacity is decreased by the number of bytes read.
   *
   * For algorithms that take an input step #PSA_KEY_DERIVATION_INPUT_SECRET,
   * the input to that step must be provided with psa_key_derivation_input_key().
   * Future versions of this specification may include additional restrictions
   * on the derived key based on the attributes and strength of the secret key.
   *
   * \param[in] attributes    The attributes for the new key.
   *                          If the key type to be created is
   *                          #PSA_KEY_TYPE_PASSWORD_HASH then the algorithm in
   *                          the policy must be the same as in the current
   *                          operation.
   * \param[in,out] operation The key derivation operation object to read from.
   * \param[out] key          On success, an identifier for the newly created
   *                          key. For persistent keys, this is the key
   *                          identifier defined in \p attributes.
   *                          \c 0 on failure.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   *         If the key is persistent, the key material and the key's metadata
   *         have been saved to persistent storage.
   * \retval #PSA_ERROR_ALREADY_EXISTS
   *         This is an attempt to create a persistent key, and there is
   *         already a persistent key with the given identifier.
   * \retval #PSA_ERROR_INSUFFICIENT_DATA
   *         There was not enough data to create the desired key.
   *         Note that in this case, no output is written to the output buffer.
   *         The operation's capacity is set to 0, thus subsequent calls to
   *         this function will not succeed, even with a smaller output buffer.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         The key type or key size is not supported, either by the
   *         implementation in general or in this particular location.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The provided key attributes are not valid for the operation.
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         The #PSA_KEY_DERIVATION_INPUT_SECRET or
   *         #PSA_KEY_DERIVATION_INPUT_PASSWORD input was not provided through a
   *         key; or one of the inputs was a key whose policy didn't allow
   *         #PSA_KEY_USAGE_DERIVE.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active and completed
   *         all required input steps).
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_INSUFFICIENT_STORAGE
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_DATA_INVALID
   * \retval #PSA_ERROR_DATA_CORRUPT
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_output_key(
      const psa_key_attributes_t *attributes,
      psa_key_derivation_operation_t *operation,
      mbedtls_svc_key_id_t *key);
  
  /** Compare output data from a key derivation operation to an expected value.
   *
   * This function calculates output bytes from a key derivation algorithm and
   * compares those bytes to an expected value in constant time.
   * If you view the key derivation's output as a stream of bytes, this
   * function destructively reads the requested number of bytes from the
   * stream before comparing them.
   * The operation's capacity decreases by the number of bytes read.
   *
   * This is functionally equivalent to the following code:
   * \code
   * psa_key_derivation_output_bytes(operation, tmp, output_length);
   * if (memcmp(output, tmp, output_length) != 0)
   *     return PSA_ERROR_INVALID_SIGNATURE;
   * \endcode
   * except (1) it works even if the key's policy does not allow outputting the
   * bytes, and (2) the comparison will be done in constant time.
   *
   * If this function returns an error status other than
   * #PSA_ERROR_INSUFFICIENT_DATA or #PSA_ERROR_INVALID_SIGNATURE,
   * the operation enters an error state and must be aborted by calling
   * psa_key_derivation_abort().
   *
   * \param[in,out] operation The key derivation operation object to read from.
   * \param[in] expected_output Buffer where the output will be written.
   * \param output_length     Length ot the expected output; this is also the
   *                          number of bytes that will be read.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_SIGNATURE
   *         The output was read successfully, but if differs from the expected
   *         output.
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         One of the inputs was a key whose policy didn't allow
   *         #PSA_KEY_USAGE_VERIFY_DERIVATION.
   * \retval #PSA_ERROR_INSUFFICIENT_DATA
   *                          The operation's capacity was less than
   *                          \p output_length bytes. Note that in this case,
   *                          the operation's capacity is set to 0, thus
   *                          subsequent calls to this function will not
   *                          succeed, even with a smaller output buffer.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active and completed
   *         all required input steps).
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_verify_bytes(
      psa_key_derivation_operation_t *operation,
      const uint8_t *expected_output,
      size_t output_length);
  
  /** Compare output data from a key derivation operation to an expected value
   * stored in a key object.
   *
   * This function calculates output bytes from a key derivation algorithm and
   * compares those bytes to an expected value, provided as key of type
   * #PSA_KEY_TYPE_PASSWORD_HASH.
   * If you view the key derivation's output as a stream of bytes, this
   * function destructively reads the number of bytes corresponding the the
   * length of the expected value from the stream before comparing them.
   * The operation's capacity decreases by the number of bytes read.
   *
   * This is functionally equivalent to exporting the key and calling
   * psa_key_derivation_verify_bytes() on the result, except that it
   * works even if the key cannot be exported.
   *
   * If this function returns an error status other than
   * #PSA_ERROR_INSUFFICIENT_DATA or #PSA_ERROR_INVALID_SIGNATURE,
   * the operation enters an error state and must be aborted by calling
   * psa_key_derivation_abort().
   *
   * \param[in,out] operation The key derivation operation object to read from.
   * \param[in] expected      A key of type #PSA_KEY_TYPE_PASSWORD_HASH
   *                          containing the expected output. Its policy must
   *                          include the #PSA_KEY_USAGE_VERIFY_DERIVATION flag
   *                          and the permitted algorithm must match the
   *                          operation. The value of this key was likely
   *                          computed by a previous call to
   *                          psa_key_derivation_output_key().
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_INVALID_SIGNATURE
   *         The output was read successfully, but if differs from the expected
   *         output.
   * \retval #PSA_ERROR_INVALID_HANDLE
   *         The key passed as the expected value does not exist.
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         The key passed as the expected value has an invalid type.
   * \retval #PSA_ERROR_NOT_PERMITTED
   *         The key passed as the expected value does not allow this usage or
   *         this algorithm; or one of the inputs was a key whose policy didn't
   *         allow #PSA_KEY_USAGE_VERIFY_DERIVATION.
   * \retval #PSA_ERROR_INSUFFICIENT_DATA
   *                          The operation's capacity was less than
   *                          the length of the expected value. In this case,
   *                          the operation's capacity is set to 0, thus
   *                          subsequent calls to this function will not
   *                          succeed, even with a smaller output buffer.
   * \retval #PSA_ERROR_BAD_STATE
   *         The operation state is not valid (it must be active and completed
   *         all required input steps).
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_verify_key(
      psa_key_derivation_operation_t *operation,
      psa_key_id_t expected);
  
  /** Abort a key derivation operation.
   *
   * Aborting an operation frees all associated resources except for the \c
   * operation structure itself. Once aborted, the operation object can be reused
   * for another operation by calling psa_key_derivation_setup() again.
   *
   * This function may be called at any time after the operation
   * object has been initialized as described in #psa_key_derivation_operation_t.
   *
   * In particular, it is valid to call psa_key_derivation_abort() twice, or to
   * call psa_key_derivation_abort() on an operation that has not been set up.
   *
   * \param[in,out] operation    The operation to abort.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_key_derivation_abort(
      psa_key_derivation_operation_t *operation);
  
  /** Perform a key agreement and return the raw shared secret.
   *
   * \warning The raw result of a key agreement algorithm such as finite-field
   * Diffie-Hellman or elliptic curve Diffie-Hellman has biases and should
   * not be used directly as key material. It should instead be passed as
   * input to a key derivation algorithm. To chain a key agreement with
   * a key derivation, use psa_key_derivation_key_agreement() and other
   * functions from the key derivation interface.
   *
   * \param alg                     The key agreement algorithm to compute
   *                                (\c PSA_ALG_XXX value such that
   *                                #PSA_ALG_IS_RAW_KEY_AGREEMENT(\p alg)
   *                                is true).
   * \param private_key             Identifier of the private key to use. It must
   *                                allow the usage #PSA_KEY_USAGE_DERIVE.
   * \param[in] peer_key            Public key of the peer. It must be
   *                                in the same format that psa_import_key()
   *                                accepts. The standard formats for public
   *                                keys are documented in the documentation
   *                                of psa_export_public_key().
   * \param peer_key_length         Size of \p peer_key in bytes.
   * \param[out] output             Buffer where the decrypted message is to
   *                                be written.
   * \param output_size             Size of the \c output buffer in bytes.
   * \param[out] output_length      On success, the number of bytes
   *                                that make up the returned output.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   * \retval #PSA_ERROR_INVALID_HANDLE
   * \retval #PSA_ERROR_NOT_PERMITTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p alg is not a key agreement algorithm
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   *         \p private_key is not compatible with \p alg,
   *         or \p peer_key is not valid for \p alg or not compatible with
   *         \p private_key.
   * \retval #PSA_ERROR_BUFFER_TOO_SMALL
   *         \p output_size is too small
   * \retval #PSA_ERROR_NOT_SUPPORTED
   *         \p alg is not a supported key agreement algorithm.
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_raw_key_agreement(psa_algorithm_t alg,
                                     mbedtls_svc_key_id_t private_key,
                                     const uint8_t *peer_key,
                                     size_t peer_key_length,
                                     uint8_t *output,
                                     size_t output_size,
                                     size_t *output_length);
  
  /**@}*/
  
  /** \defgroup random Random generation
   * @{
   */
  
  /**
   * \brief Generate random bytes.
   *
   * \warning This function **can** fail! Callers MUST check the return status
   *          and MUST NOT use the content of the output buffer if the return
   *          status is not #PSA_SUCCESS.
   *
   * \note    To generate a key, use psa_generate_key() instead.
   *
   * \param[out] output       Output buffer for the generated data.
   * \param output_size       Number of bytes to generate and output.
   *
   * \retval #PSA_SUCCESS
   * \retval #PSA_ERROR_NOT_SUPPORTED
   * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_generate_random(uint8_t *output,
                                   size_t output_size);
  
  /**
   * \brief Generate a key or key pair.
   *
   * The key is generated randomly.
   * Its location, usage policy, type and size are taken from \p attributes.
   *
   * Implementations must reject an attempt to generate a key of size 0.
   *
   * The following type-specific considerations apply:
   * - For RSA keys (#PSA_KEY_TYPE_RSA_KEY_PAIR),
   *   the public exponent is 65537.
   *   The modulus is a product of two probabilistic primes
   *   between 2^{n-1} and 2^n where n is the bit size specified in the
   *   attributes.
   *
   * \param[in] attributes    The attributes for the new key.
   * \param[out] key          On success, an identifier for the newly created
   *                          key. For persistent keys, this is the key
   *                          identifier defined in \p attributes.
   *                          \c 0 on failure.
   *
   * \retval #PSA_SUCCESS
   *         Success.
   *         If the key is persistent, the key material and the key's metadata
   *         have been saved to persistent storage.
   * \retval #PSA_ERROR_ALREADY_EXISTS
   *         This is an attempt to create a persistent key, and there is
   *         already a persistent key with the given identifier.
   * \retval #PSA_ERROR_NOT_SUPPORTED
   * \retval #PSA_ERROR_INVALID_ARGUMENT
   * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
   * \retval #PSA_ERROR_INSUFFICIENT_ENTROPY
   * \retval #PSA_ERROR_COMMUNICATION_FAILURE
   * \retval #PSA_ERROR_HARDWARE_FAILURE
   * \retval #PSA_ERROR_CORRUPTION_DETECTED
   * \retval #PSA_ERROR_INSUFFICIENT_STORAGE
   * \retval #PSA_ERROR_DATA_INVALID
   * \retval #PSA_ERROR_DATA_CORRUPT
   * \retval #PSA_ERROR_STORAGE_FAILURE
   * \retval #PSA_ERROR_BAD_STATE
   *         The library has not been previously initialized by psa_crypto_init().
   *         It is implementation-dependent whether a failure to initialize
   *         results in this error code.
   */
  psa_status_t psa_generate_key(const psa_key_attributes_t *attributes,
                                mbedtls_svc_key_id_t *key);
  
  /**@}*/
  
  #ifdef __cplusplus
  }
  #endif
  
  /* The file "crypto_sizes.h" contains definitions for size calculation
   * macros whose definitions are implementation-specific. */
  #include "crypto_sizes.h"
  
  /* The file "crypto_struct.h" contains definitions for
   * implementation-specific structs that are declared above. */
  #include "crypto_struct.h"
  
  /* The file "crypto_extra.h" contains vendor-specific definitions. This
   * can include vendor-defined algorithms, extra functions, etc. */
  #include "crypto_extra.h"
  
  #endif /* PSA_CRYPTO_H */
  