text: /*
   * DES encryption/decryption
   * Copyright (c) 2007 Reimar Doeffinger
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #ifndef AVUTIL_DES_H
  #define AVUTIL_DES_H
  
  #include <stdint.h>
  
  /**
   * @defgroup lavu_des DES
   * @ingroup lavu_crypto
   * @{
   */
  
  typedef struct AVDES {
      uint64_t round_keys[3][16];
      int triple_des;
  } AVDES;
  
  /**
   * Allocate an AVDES context.
   */
  AVDES *av_des_alloc(void);
  
  /**
   * @brief Initializes an AVDES context.
   *
   * @param key_bits must be 64 or 192
   * @param decrypt 0 for encryption/CBC-MAC, 1 for decryption
   * @return zero on success, negative value otherwise
   */
  int av_des_init(struct AVDES *d, const uint8_t *key, int key_bits, int decrypt);
  
  /**
   * @brief Encrypts / decrypts using the DES algorithm.
   *
   * @param count number of 8 byte blocks
   * @param dst destination array, can be equal to src, must be 8-byte aligned
   * @param src source array, can be equal to dst, must be 8-byte aligned, may be NULL
   * @param iv initialization vector for CBC mode, if NULL then ECB will be used,
   *           must be 8-byte aligned
   * @param decrypt 0 for encryption, 1 for decryption
   */
  void av_des_crypt(struct AVDES *d, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt);
  
  /**
   * @brief Calculates CBC-MAC using the DES algorithm.
   *
   * @param count number of 8 byte blocks
   * @param dst destination array, can be equal to src, must be 8-byte aligned
   * @param src source array, can be equal to dst, must be 8-byte aligned, may be NULL
   */
  void av_des_mac(struct AVDES *d, uint8_t *dst, const uint8_t *src, int count);
  
  /**
   * @}
   */
  
  #endif /* AVUTIL_DES_H */
  