text: /*
   * Copyright (C) 2015-2018 Alibaba Group Holding Limited
   */
  
  
  
  #ifndef MBEDTLS_DES_H
  #define MBEDTLS_DES_H
  
  #if !defined(MBEDTLS_CONFIG_FILE)
  #include "config.h"
  #else
  #include MBEDTLS_CONFIG_FILE
  #endif
  
  #include <stddef.h>
  #include <stdint.h>
  
  #define MBEDTLS_DES_ENCRYPT     1
  #define MBEDTLS_DES_DECRYPT     0
  
  #define MBEDTLS_ERR_DES_INVALID_INPUT_LENGTH              -0x0032  /**< The data input has an invalid length. */
  
  #define MBEDTLS_DES_KEY_SIZE    8
  
  #if !defined(MBEDTLS_DES_ALT)
  // Regular implementation
  //
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * \brief          DES context structure
   */
  typedef struct
  {
      uint32_t sk[32];            /*!<  DES subkeys       */
  }
  mbedtls_des_context;
  
  /**
   * \brief          Triple-DES context structure
   */
  typedef struct
  {
      uint32_t sk[96];            /*!<  3DES subkeys      */
  }
  mbedtls_des3_context;
  
  /**
   * \brief          Initialize DES context
   *
   * \param ctx      DES context to be initialized
   */
  void mbedtls_des_init( mbedtls_des_context *ctx );
  
  /**
   * \brief          Clear DES context
   *
   * \param ctx      DES context to be cleared
   */
  void mbedtls_des_free( mbedtls_des_context *ctx );
  
  /**
   * \brief          Initialize Triple-DES context
   *
   * \param ctx      DES3 context to be initialized
   */
  void mbedtls_des3_init( mbedtls_des3_context *ctx );
  
  /**
   * \brief          Clear Triple-DES context
   *
   * \param ctx      DES3 context to be cleared
   */
  void mbedtls_des3_free( mbedtls_des3_context *ctx );
  
  /**
   * \brief          Set key parity on the given key to odd.
   *
   *                 DES keys are 56 bits long, but each byte is padded with
   *                 a parity bit to allow verification.
   *
   * \param key      8-byte secret key
   */
  void mbedtls_des_key_set_parity( unsigned char key[MBEDTLS_DES_KEY_SIZE] );
  
  /**
   * \brief          Check that key parity on the given key is odd.
   *
   *                 DES keys are 56 bits long, but each byte is padded with
   *                 a parity bit to allow verification.
   *
   * \param key      8-byte secret key
   *
   * \return         0 is parity was ok, 1 if parity was not correct.
   */
  int mbedtls_des_key_check_key_parity( const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
  
  /**
   * \brief          Check that key is not a weak or semi-weak DES key
   *
   * \param key      8-byte secret key
   *
   * \return         0 if no weak key was found, 1 if a weak key was identified.
   */
  int mbedtls_des_key_check_weak( const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
  
  /**
   * \brief          DES key schedule (56-bit, encryption)
   *
   * \param ctx      DES context to be initialized
   * \param key      8-byte secret key
   *
   * \return         0
   */
  int mbedtls_des_setkey_enc( mbedtls_des_context *ctx, const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
  
  /**
   * \brief          DES key schedule (56-bit, decryption)
   *
   * \param ctx      DES context to be initialized
   * \param key      8-byte secret key
   *
   * \return         0
   */
  int mbedtls_des_setkey_dec( mbedtls_des_context *ctx, const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
  
  /**
   * \brief          Triple-DES key schedule (112-bit, encryption)
   *
   * \param ctx      3DES context to be initialized
   * \param key      16-byte secret key
   *
   * \return         0
   */
  int mbedtls_des3_set2key_enc( mbedtls_des3_context *ctx,
                        const unsigned char key[MBEDTLS_DES_KEY_SIZE * 2] );
  
  /**
   * \brief          Triple-DES key schedule (112-bit, decryption)
   *
   * \param ctx      3DES context to be initialized
   * \param key      16-byte secret key
   *
   * \return         0
   */
  int mbedtls_des3_set2key_dec( mbedtls_des3_context *ctx,
                        const unsigned char key[MBEDTLS_DES_KEY_SIZE * 2] );
  
  /**
   * \brief          Triple-DES key schedule (168-bit, encryption)
   *
   * \param ctx      3DES context to be initialized
   * \param key      24-byte secret key
   *
   * \return         0
   */
  int mbedtls_des3_set3key_enc( mbedtls_des3_context *ctx,
                        const unsigned char key[MBEDTLS_DES_KEY_SIZE * 3] );
  
  /**
   * \brief          Triple-DES key schedule (168-bit, decryption)
   *
   * \param ctx      3DES context to be initialized
   * \param key      24-byte secret key
   *
   * \return         0
   */
  int mbedtls_des3_set3key_dec( mbedtls_des3_context *ctx,
                        const unsigned char key[MBEDTLS_DES_KEY_SIZE * 3] );
  
  /**
   * \brief          DES-ECB block encryption/decryption
   *
   * \param ctx      DES context
   * \param input    64-bit input block
   * \param output   64-bit output block
   *
   * \return         0 if successful
   */
  int mbedtls_des_crypt_ecb( mbedtls_des_context *ctx,
                      const unsigned char input[8],
                      unsigned char output[8] );
  
  #if defined(MBEDTLS_CIPHER_MODE_CBC)
  /**
   * \brief          DES-CBC buffer encryption/decryption
   *
   * \note           Upon exit, the content of the IV is updated so that you can
   *                 call the function same function again on the following
   *                 block(s) of data and get the same result as if it was
   *                 encrypted in one call. This allows a "streaming" usage.
   *                 If on the other hand you need to retain the contents of the
   *                 IV, you should either save it manually or use the cipher
   *                 module instead.
   *
   * \param ctx      DES context
   * \param mode     MBEDTLS_DES_ENCRYPT or MBEDTLS_DES_DECRYPT
   * \param length   length of the input data
   * \param iv       initialization vector (updated after use)
   * \param input    buffer holding the input data
   * \param output   buffer holding the output data
   */
  int mbedtls_des_crypt_cbc( mbedtls_des_context *ctx,
                      int mode,
                      size_t length,
                      unsigned char iv[8],
                      const unsigned char *input,
                      unsigned char *output );
  #endif /* MBEDTLS_CIPHER_MODE_CBC */
  
  /**
   * \brief          3DES-ECB block encryption/decryption
   *
   * \param ctx      3DES context
   * \param input    64-bit input block
   * \param output   64-bit output block
   *
   * \return         0 if successful
   */
  int mbedtls_des3_crypt_ecb( mbedtls_des3_context *ctx,
                       const unsigned char input[8],
                       unsigned char output[8] );
  
  #if defined(MBEDTLS_CIPHER_MODE_CBC)
  /**
   * \brief          3DES-CBC buffer encryption/decryption
   *
   * \note           Upon exit, the content of the IV is updated so that you can
   *                 call the function same function again on the following
   *                 block(s) of data and get the same result as if it was
   *                 encrypted in one call. This allows a "streaming" usage.
   *                 If on the other hand you need to retain the contents of the
   *                 IV, you should either save it manually or use the cipher
   *                 module instead.
   *
   * \param ctx      3DES context
   * \param mode     MBEDTLS_DES_ENCRYPT or MBEDTLS_DES_DECRYPT
   * \param length   length of the input data
   * \param iv       initialization vector (updated after use)
   * \param input    buffer holding the input data
   * \param output   buffer holding the output data
   *
   * \return         0 if successful, or MBEDTLS_ERR_DES_INVALID_INPUT_LENGTH
   */
  int mbedtls_des3_crypt_cbc( mbedtls_des3_context *ctx,
                       int mode,
                       size_t length,
                       unsigned char iv[8],
                       const unsigned char *input,
                       unsigned char *output );
  #endif /* MBEDTLS_CIPHER_MODE_CBC */
  
  /**
   * \brief          Internal function for key expansion.
   *                 (Only exposed to allow overriding it,
   *                 see MBEDTLS_DES_SETKEY_ALT)
   *
   * \param SK       Round keys
   * \param key      Base key
   */
  void mbedtls_des_setkey( uint32_t SK[32],
                           const unsigned char key[MBEDTLS_DES_KEY_SIZE] );
  #ifdef __cplusplus
  }
  #endif
  
  #else  /* MBEDTLS_DES_ALT */
  #include "des_alt.h"
  #endif /* MBEDTLS_DES_ALT */
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * \brief          Checkup routine
   *
   * \return         0 if successful, or 1 if the test failed
   */
  int mbedtls_des_self_test( int verbose );
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* des.h */
  