text: /**
   * \file sha2.h
   *
   *  Copyright (C) 2006-2010, Brainspark B.V.
   *
   *  This file is part of PolarSSL (http://www.polarssl.org)
   *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
   *
   *  All rights reserved.
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation; either version 2 of the License, or
   *  (at your option) any later version.
   *
   *  This program 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 General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License along
   *  with this program; if not, write to the Free Software Foundation, Inc.,
   *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
   */
  #ifndef __POLARSSL_SHA2_H__
  #define __POLARSSL_SHA2_H__
  
  
  /**
   * \brief          SHA-256 context structure
   */
  typedef struct{
      unsigned long total[2];     /*!< number of bytes processed  */
      unsigned long state[8];     /*!< intermediate digest state  */
      unsigned char buffer[64];   /*!< data block being processed */
  
      unsigned char ipad[64];     /*!< HMAC: inner padding        */
      unsigned char opad[64];     /*!< HMAC: outer padding        */
      int is224;                  /*!< 0 => SHA-256, else SHA-224 */
  } sha2_context;
  
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  
  /**
   * \brief          SHA-256 context setup
   *
   * \param ctx      context to be initialized
   * \param is224    0 = use SHA256, 1 = use SHA224
   */
  void sha2_starts( sha2_context *ctx, int is224 );
  
  /**
   * \brief          SHA-256 process buffer
   *
   * \param ctx      SHA-256 context
   * \param input    buffer holding the  data
   * \param ilen     length of the input data
   */
  void sha2_update( sha2_context *ctx, const unsigned char *input, int ilen );
  
  /**
   * \brief          SHA-256 final digest
   *
   * \param ctx      SHA-256 context
   * \param output   SHA-224/256 checksum result
   */
  void sha2_finish( sha2_context *ctx, unsigned char output[32] );
  
  /**
   * \brief          Output = SHA-256( input buffer )
   *
   * \param input    buffer holding the  data
   * \param ilen     length of the input data
   * \param output   SHA-224/256 checksum result
   * \param is224    0 = use SHA256, 1 = use SHA224
   */
  void sha2( const unsigned char *input, int ilen,
             unsigned char output[32], int is224 );
  
  /**
   * \brief          Output = SHA-256( file contents )
   *
   * \param path     input file name
   * \param output   SHA-224/256 checksum result
   * \param is224    0 = use SHA256, 1 = use SHA224
   *
   * \return         0 if successful, 1 if fopen failed,
   *                 or 2 if fread failed
   */
  int sha2_file( const char *path, unsigned char output[32], int is224 );
  
  /**
   * \brief          SHA-256 HMAC context setup
   *
   * \param ctx      HMAC context to be initialized
   * \param key      HMAC secret key
   * \param keylen   length of the HMAC key
   * \param is224    0 = use SHA256, 1 = use SHA224
   */
  void sha2_hmac_starts( sha2_context *ctx, const unsigned char *key, int keylen,
                         int is224 );
  
  /**
   * \brief          SHA-256 HMAC process buffer
   *
   * \param ctx      HMAC context
   * \param input    buffer holding the  data
   * \param ilen     length of the input data
   */
  void sha2_hmac_update( sha2_context *ctx, const unsigned char *input, int ilen );
  
  /**
   * \brief          SHA-256 HMAC final digest
   *
   * \param ctx      HMAC context
   * \param output   SHA-224/256 HMAC checksum result
   */
  void sha2_hmac_finish( sha2_context *ctx, unsigned char output[32] );
  
  /**
   * \brief          SHA-256 HMAC context reset
   *
   * \param ctx      HMAC context to be reset
   */
  void sha2_hmac_reset( sha2_context *ctx );
  
  /**
   * \brief          Output = HMAC-SHA-256( hmac key, input buffer )
   *
   * \param key      HMAC secret key
   * \param keylen   length of the HMAC key
   * \param input    buffer holding the  data
   * \param ilen     length of the input data
   * \param output   HMAC-SHA-224/256 result
   * \param is224    0 = use SHA256, 1 = use SHA224
   */
  void sha2_hmac( const unsigned char *key, int keylen,
                  const unsigned char *input, int ilen,
                  unsigned char output[32], int is224 );
  
  /**
   * \brief          Checkup routine
   *
   * \return         0 if successful, or 1 if the test failed
   */
  int sha2_self_test( int verbose );
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif   // __POLARSSL_SHA2_H__ /* sha2.h */
  