text: /* Copyright (c) 2014, Google Inc.
   *
   * Permission to use, copy, modify, and/or distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
   * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
   * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
   * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
  
  #ifndef OPENSSL_HEADER_AEAD_H
  #define OPENSSL_HEADER_AEAD_H
  
  #include <openssl_grpc/base.h>
  
  #if defined(__cplusplus)
  extern "C" {
  #endif
  
  
  // Authenticated Encryption with Additional Data.
  //
  // AEAD couples confidentiality and integrity in a single primitive. AEAD
  // algorithms take a key and then can seal and open individual messages. Each
  // message has a unique, per-message nonce and, optionally, additional data
  // which is authenticated but not included in the ciphertext.
  //
  // The |EVP_AEAD_CTX_init| function initialises an |EVP_AEAD_CTX| structure and
  // performs any precomputation needed to use |aead| with |key|. The length of
  // the key, |key_len|, is given in bytes.
  //
  // The |tag_len| argument contains the length of the tags, in bytes, and allows
  // for the processing of truncated authenticators. A zero value indicates that
  // the default tag length should be used and this is defined as
  // |EVP_AEAD_DEFAULT_TAG_LENGTH| in order to make the code clear. Using
  // truncated tags increases an attacker's chance of creating a valid forgery.
  // Be aware that the attacker's chance may increase more than exponentially as
  // would naively be expected.
  //
  // When no longer needed, the initialised |EVP_AEAD_CTX| structure must be
  // passed to |EVP_AEAD_CTX_cleanup|, which will deallocate any memory used.
  //
  // With an |EVP_AEAD_CTX| in hand, one can seal and open messages. These
  // operations are intended to meet the standard notions of privacy and
  // authenticity for authenticated encryption. For formal definitions see
  // Bellare and Namprempre, "Authenticated encryption: relations among notions
  // and analysis of the generic composition paradigm," Lecture Notes in Computer
  // Science B<1976> (2000), 531–545,
  // http://www-cse.ucsd.edu/~mihir/papers/oem.html.
  //
  // When sealing messages, a nonce must be given. The length of the nonce is
  // fixed by the AEAD in use and is returned by |EVP_AEAD_nonce_length|. *The
  // nonce must be unique for all messages with the same key*. This is critically
  // important - nonce reuse may completely undermine the security of the AEAD.
  // Nonces may be predictable and public, so long as they are unique. Uniqueness
  // may be achieved with a simple counter or, if large enough, may be generated
  // randomly. The nonce must be passed into the "open" operation by the receiver
  // so must either be implicit (e.g. a counter), or must be transmitted along
  // with the sealed message.
  //
  // The "seal" and "open" operations are atomic - an entire message must be
  // encrypted or decrypted in a single call. Large messages may have to be split
  // up in order to accommodate this. When doing so, be mindful of the need not to
  // repeat nonces and the possibility that an attacker could duplicate, reorder
  // or drop message chunks. For example, using a single key for a given (large)
  // message and sealing chunks with nonces counting from zero would be secure as
  // long as the number of chunks was securely transmitted. (Otherwise an
  // attacker could truncate the message by dropping chunks from the end.)
  //
  // The number of chunks could be transmitted by prefixing it to the plaintext,
  // for example. This also assumes that no other message would ever use the same
  // key otherwise the rule that nonces must be unique for a given key would be
  // violated.
  //
  // The "seal" and "open" operations also permit additional data to be
  // authenticated via the |ad| parameter. This data is not included in the
  // ciphertext and must be identical for both the "seal" and "open" call. This
  // permits implicit context to be authenticated but may be empty if not needed.
  //
  // The "seal" and "open" operations may work in-place if the |out| and |in|
  // arguments are equal. Otherwise, if |out| and |in| alias, input data may be
  // overwritten before it is read. This situation will cause an error.
  //
  // The "seal" and "open" operations return one on success and zero on error.
  
  
  // AEAD algorithms.
  
  // EVP_aead_aes_128_gcm is AES-128 in Galois Counter Mode.
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_gcm(void);
  
  // EVP_aead_aes_256_gcm is AES-256 in Galois Counter Mode.
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_gcm(void);
  
  // EVP_aead_chacha20_poly1305 is the AEAD built from ChaCha20 and
  // Poly1305 as described in RFC 7539.
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_chacha20_poly1305(void);
  
  // EVP_aead_aes_128_ctr_hmac_sha256 is AES-128 in CTR mode with HMAC-SHA256 for
  // authentication. The nonce is 12 bytes; the bottom 32-bits are used as the
  // block counter, thus the maximum plaintext size is 64GB.
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_ctr_hmac_sha256(void);
  
  // EVP_aead_aes_256_ctr_hmac_sha256 is AES-256 in CTR mode with HMAC-SHA256 for
  // authentication. See |EVP_aead_aes_128_ctr_hmac_sha256| for details.
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_ctr_hmac_sha256(void);
  
  // EVP_aead_aes_128_gcm_siv is AES-128 in GCM-SIV mode. See
  // https://tools.ietf.org/html/draft-irtf-cfrg-gcmsiv-02
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_gcm_siv(void);
  
  // EVP_aead_aes_256_gcm_siv is AES-256 in GCM-SIV mode. See
  // https://tools.ietf.org/html/draft-irtf-cfrg-gcmsiv-02
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_gcm_siv(void);
  
  // EVP_aead_aes_128_ccm_bluetooth is AES-128-CCM with M=4 and L=2 (4-byte tags
  // and 13-byte nonces), as decribed in the Bluetooth Core Specification v5.0,
  // Volume 6, Part E, Section 1.
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_ccm_bluetooth(void);
  
  // EVP_aead_aes_128_ccm_bluetooth_8 is AES-128-CCM with M=8 and L=2 (8-byte tags
  // and 13-byte nonces), as used in the Bluetooth Mesh Networking Specification
  // v1.0.
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_ccm_bluetooth_8(void);
  
  // EVP_has_aes_hardware returns one if we enable hardware support for fast and
  // constant-time AES-GCM.
  OPENSSL_EXPORT int EVP_has_aes_hardware(void);
  
  
  // Utility functions.
  
  // EVP_AEAD_key_length returns the length, in bytes, of the keys used by
  // |aead|.
  OPENSSL_EXPORT size_t EVP_AEAD_key_length(const EVP_AEAD *aead);
  
  // EVP_AEAD_nonce_length returns the length, in bytes, of the per-message nonce
  // for |aead|.
  OPENSSL_EXPORT size_t EVP_AEAD_nonce_length(const EVP_AEAD *aead);
  
  // EVP_AEAD_max_overhead returns the maximum number of additional bytes added
  // by the act of sealing data with |aead|.
  OPENSSL_EXPORT size_t EVP_AEAD_max_overhead(const EVP_AEAD *aead);
  
  // EVP_AEAD_max_tag_len returns the maximum tag length when using |aead|. This
  // is the largest value that can be passed as |tag_len| to
  // |EVP_AEAD_CTX_init|.
  OPENSSL_EXPORT size_t EVP_AEAD_max_tag_len(const EVP_AEAD *aead);
  
  
  // AEAD operations.
  
  // An EVP_AEAD_CTX represents an AEAD algorithm configured with a specific key
  // and message-independent IV.
  typedef struct evp_aead_ctx_st {
    const EVP_AEAD *aead;
    // aead_state is an opaque pointer to whatever state the AEAD needs to
    // maintain.
    void *aead_state;
    // tag_len may contain the actual length of the authentication tag if it is
    // known at initialization time.
    uint8_t tag_len;
  } EVP_AEAD_CTX;
  
  // EVP_AEAD_MAX_KEY_LENGTH contains the maximum key length used by
  // any AEAD defined in this header.
  #define EVP_AEAD_MAX_KEY_LENGTH 80
  
  // EVP_AEAD_MAX_NONCE_LENGTH contains the maximum nonce length used by
  // any AEAD defined in this header.
  #define EVP_AEAD_MAX_NONCE_LENGTH 16
  
  // EVP_AEAD_MAX_OVERHEAD contains the maximum overhead used by any AEAD
  // defined in this header.
  #define EVP_AEAD_MAX_OVERHEAD 64
  
  // EVP_AEAD_DEFAULT_TAG_LENGTH is a magic value that can be passed to
  // EVP_AEAD_CTX_init to indicate that the default tag length for an AEAD should
  // be used.
  #define EVP_AEAD_DEFAULT_TAG_LENGTH 0
  
  // EVP_AEAD_CTX_zero sets an uninitialized |ctx| to the zero state. It must be
  // initialized with |EVP_AEAD_CTX_init| before use. It is safe, but not
  // necessary, to call |EVP_AEAD_CTX_cleanup| in this state. This may be used for
  // more uniform cleanup of |EVP_AEAD_CTX|.
  OPENSSL_EXPORT void EVP_AEAD_CTX_zero(EVP_AEAD_CTX *ctx);
  
  // EVP_AEAD_CTX_new allocates an |EVP_AEAD_CTX|, calls |EVP_AEAD_CTX_init| and
  // returns the |EVP_AEAD_CTX|, or NULL on error.
  OPENSSL_EXPORT EVP_AEAD_CTX *EVP_AEAD_CTX_new(const EVP_AEAD *aead,
                                                const uint8_t *key,
                                                size_t key_len, size_t tag_len);
  
  // EVP_AEAD_CTX_free calls |EVP_AEAD_CTX_cleanup| and |OPENSSL_free| on
  // |ctx|.
  OPENSSL_EXPORT void EVP_AEAD_CTX_free(EVP_AEAD_CTX *ctx);
  
  // EVP_AEAD_CTX_init initializes |ctx| for the given AEAD algorithm. The |impl|
  // argument is ignored and should be NULL. Authentication tags may be truncated
  // by passing a size as |tag_len|. A |tag_len| of zero indicates the default
  // tag length and this is defined as EVP_AEAD_DEFAULT_TAG_LENGTH for
  // readability.
  //
  // Returns 1 on success. Otherwise returns 0 and pushes to the error stack. In
  // the error case, you do not need to call |EVP_AEAD_CTX_cleanup|, but it's
  // harmless to do so.
  OPENSSL_EXPORT int EVP_AEAD_CTX_init(EVP_AEAD_CTX *ctx, const EVP_AEAD *aead,
                                       const uint8_t *key, size_t key_len,
                                       size_t tag_len, ENGINE *impl);
  
  // EVP_AEAD_CTX_cleanup frees any data allocated by |ctx|. It is a no-op to
  // call |EVP_AEAD_CTX_cleanup| on a |EVP_AEAD_CTX| that has been |memset| to
  // all zeros.
  OPENSSL_EXPORT void EVP_AEAD_CTX_cleanup(EVP_AEAD_CTX *ctx);
  
  // EVP_AEAD_CTX_seal encrypts and authenticates |in_len| bytes from |in| and
  // authenticates |ad_len| bytes from |ad| and writes the result to |out|. It
  // returns one on success and zero otherwise.
  //
  // This function may be called concurrently with itself or any other seal/open
  // function on the same |EVP_AEAD_CTX|.
  //
  // At most |max_out_len| bytes are written to |out| and, in order to ensure
  // success, |max_out_len| should be |in_len| plus the result of
  // |EVP_AEAD_max_overhead|. On successful return, |*out_len| is set to the
  // actual number of bytes written.
  //
  // The length of |nonce|, |nonce_len|, must be equal to the result of
  // |EVP_AEAD_nonce_length| for this AEAD.
  //
  // |EVP_AEAD_CTX_seal| never results in a partial output. If |max_out_len| is
  // insufficient, zero will be returned. If any error occurs, |out| will be
  // filled with zero bytes and |*out_len| set to zero.
  //
  // If |in| and |out| alias then |out| must be == |in|.
  OPENSSL_EXPORT int EVP_AEAD_CTX_seal(const EVP_AEAD_CTX *ctx, uint8_t *out,
                                       size_t *out_len, size_t max_out_len,
                                       const uint8_t *nonce, size_t nonce_len,
                                       const uint8_t *in, size_t in_len,
                                       const uint8_t *ad, size_t ad_len);
  
  // EVP_AEAD_CTX_open authenticates |in_len| bytes from |in| and |ad_len| bytes
  // from |ad| and decrypts at most |in_len| bytes into |out|. It returns one on
  // success and zero otherwise.
  //
  // This function may be called concurrently with itself or any other seal/open
  // function on the same |EVP_AEAD_CTX|.
  //
  // At most |in_len| bytes are written to |out|. In order to ensure success,
  // |max_out_len| should be at least |in_len|. On successful return, |*out_len|
  // is set to the the actual number of bytes written.
  //
  // The length of |nonce|, |nonce_len|, must be equal to the result of
  // |EVP_AEAD_nonce_length| for this AEAD.
  //
  // |EVP_AEAD_CTX_open| never results in a partial output. If |max_out_len| is
  // insufficient, zero will be returned. If any error occurs, |out| will be
  // filled with zero bytes and |*out_len| set to zero.
  //
  // If |in| and |out| alias then |out| must be == |in|.
  OPENSSL_EXPORT int EVP_AEAD_CTX_open(const EVP_AEAD_CTX *ctx, uint8_t *out,
                                       size_t *out_len, size_t max_out_len,
                                       const uint8_t *nonce, size_t nonce_len,
                                       const uint8_t *in, size_t in_len,
                                       const uint8_t *ad, size_t ad_len);
  
  // EVP_AEAD_CTX_seal_scatter encrypts and authenticates |in_len| bytes from |in|
  // and authenticates |ad_len| bytes from |ad|. It writes |in_len| bytes of
  // ciphertext to |out| and the authentication tag to |out_tag|. It returns one
  // on success and zero otherwise.
  //
  // This function may be called concurrently with itself or any other seal/open
  // function on the same |EVP_AEAD_CTX|.
  //
  // Exactly |in_len| bytes are written to |out|, and up to
  // |EVP_AEAD_max_overhead+extra_in_len| bytes to |out_tag|. On successful
  // return, |*out_tag_len| is set to the actual number of bytes written to
  // |out_tag|.
  //
  // |extra_in| may point to an additional plaintext input buffer if the cipher
  // supports it. If present, |extra_in_len| additional bytes of plaintext are
  // encrypted and authenticated, and the ciphertext is written (before the tag)
  // to |out_tag|. |max_out_tag_len| must be sized to allow for the additional
  // |extra_in_len| bytes.
  //
  // The length of |nonce|, |nonce_len|, must be equal to the result of
  // |EVP_AEAD_nonce_length| for this AEAD.
  //
  // |EVP_AEAD_CTX_seal_scatter| never results in a partial output. If
  // |max_out_tag_len| is insufficient, zero will be returned. If any error
  // occurs, |out| and |out_tag| will be filled with zero bytes and |*out_tag_len|
  // set to zero.
  //
  // If |in| and |out| alias then |out| must be == |in|. |out_tag| may not alias
  // any other argument.
  OPENSSL_EXPORT int EVP_AEAD_CTX_seal_scatter(
      const EVP_AEAD_CTX *ctx, uint8_t *out,
      uint8_t *out_tag, size_t *out_tag_len, size_t max_out_tag_len,
      const uint8_t *nonce, size_t nonce_len,
      const uint8_t *in, size_t in_len,
      const uint8_t *extra_in, size_t extra_in_len,
      const uint8_t *ad, size_t ad_len);
  
  // EVP_AEAD_CTX_open_gather decrypts and authenticates |in_len| bytes from |in|
  // and authenticates |ad_len| bytes from |ad| using |in_tag_len| bytes of
  // authentication tag from |in_tag|. If successful, it writes |in_len| bytes of
  // plaintext to |out|. It returns one on success and zero otherwise.
  //
  // This function may be called concurrently with itself or any other seal/open
  // function on the same |EVP_AEAD_CTX|.
  //
  // The length of |nonce|, |nonce_len|, must be equal to the result of
  // |EVP_AEAD_nonce_length| for this AEAD.
  //
  // |EVP_AEAD_CTX_open_gather| never results in a partial output. If any error
  // occurs, |out| will be filled with zero bytes.
  //
  // If |in| and |out| alias then |out| must be == |in|.
  OPENSSL_EXPORT int EVP_AEAD_CTX_open_gather(
      const EVP_AEAD_CTX *ctx, uint8_t *out, const uint8_t *nonce,
      size_t nonce_len, const uint8_t *in, size_t in_len, const uint8_t *in_tag,
      size_t in_tag_len, const uint8_t *ad, size_t ad_len);
  
  // EVP_AEAD_CTX_aead returns the underlying AEAD for |ctx|, or NULL if one has
  // not been set.
  OPENSSL_EXPORT const EVP_AEAD *EVP_AEAD_CTX_aead(const EVP_AEAD_CTX *ctx);
  
  
  // TLS-specific AEAD algorithms.
  //
  // These AEAD primitives do not meet the definition of generic AEADs. They are
  // all specific to TLS and should not be used outside of that context. They must
  // be initialized with |EVP_AEAD_CTX_init_with_direction|, are stateful, and may
  // not be used concurrently. Any nonces are used as IVs, so they must be
  // unpredictable. They only accept an |ad| parameter of length 11 (the standard
  // TLS one with length omitted).
  
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls(void);
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls_implicit_iv(void);
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha256_tls(void);
  
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls(void);
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls_implicit_iv(void);
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha256_tls(void);
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha384_tls(void);
  
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls(void);
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls_implicit_iv(void);
  
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_null_sha1_tls(void);
  
  // EVP_aead_aes_128_gcm_tls12 is AES-128 in Galois Counter Mode using the TLS
  // 1.2 nonce construction.
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_gcm_tls12(void);
  
  // EVP_aead_aes_256_gcm_tls12 is AES-256 in Galois Counter Mode using the TLS
  // 1.2 nonce construction.
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_gcm_tls12(void);
  
  
  // SSLv3-specific AEAD algorithms.
  //
  // These AEAD primitives do not meet the definition of generic AEADs. They are
  // all specific to SSLv3 and should not be used outside of that context. They
  // must be initialized with |EVP_AEAD_CTX_init_with_direction|, are stateful,
  // and may not be used concurrently. They only accept an |ad| parameter of
  // length 9 (the standard TLS one with length and version omitted).
  
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_ssl3(void);
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_ssl3(void);
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_ssl3(void);
  OPENSSL_EXPORT const EVP_AEAD *EVP_aead_null_sha1_ssl3(void);
  
  
  // Obscure functions.
  
  // evp_aead_direction_t denotes the direction of an AEAD operation.
  enum evp_aead_direction_t {
    evp_aead_open,
    evp_aead_seal,
  };
  
  // EVP_AEAD_CTX_init_with_direction calls |EVP_AEAD_CTX_init| for normal
  // AEADs. For TLS-specific and SSL3-specific AEADs, it initializes |ctx| for a
  // given direction.
  OPENSSL_EXPORT int EVP_AEAD_CTX_init_with_direction(
      EVP_AEAD_CTX *ctx, const EVP_AEAD *aead, const uint8_t *key, size_t key_len,
      size_t tag_len, enum evp_aead_direction_t dir);
  
  // EVP_AEAD_CTX_get_iv sets |*out_len| to the length of the IV for |ctx| and
  // sets |*out_iv| to point to that many bytes of the current IV. This is only
  // meaningful for AEADs with implicit IVs (i.e. CBC mode in SSLv3 and TLS 1.0).
  //
  // It returns one on success or zero on error.
  OPENSSL_EXPORT int EVP_AEAD_CTX_get_iv(const EVP_AEAD_CTX *ctx,
                                         const uint8_t **out_iv, size_t *out_len);
  
  // EVP_AEAD_CTX_tag_len computes the exact byte length of the tag written by
  // |EVP_AEAD_CTX_seal_scatter| and writes it to |*out_tag_len|. It returns one
  // on success or zero on error. |in_len| and |extra_in_len| must equal the
  // arguments of the same names passed to |EVP_AEAD_CTX_seal_scatter|.
  OPENSSL_EXPORT int EVP_AEAD_CTX_tag_len(const EVP_AEAD_CTX *ctx,
                                          size_t *out_tag_len,
                                          const size_t in_len,
                                          const size_t extra_in_len);
  
  
  #if defined(__cplusplus)
  }  // extern C
  
  #if !defined(BORINGSSL_NO_CXX)
  extern "C++" {
  
  namespace bssl {
  
  using ScopedEVP_AEAD_CTX =
      internal::StackAllocated<EVP_AEAD_CTX, void, EVP_AEAD_CTX_zero,
                               EVP_AEAD_CTX_cleanup>;
  
  BORINGSSL_MAKE_DELETER(EVP_AEAD_CTX, EVP_AEAD_CTX_free)
  
  }  // namespace bssl
  
  }  // extern C++
  #endif
  
  #endif
  
  #endif  // OPENSSL_HEADER_AEAD_H
  