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RIOT/sys/include/hashes/md5.h 4.36 KB
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  /*
   * Copyright (C) 2003-2005 by Christopher R. Hertel
   *               2015 Freie Universitรคt Berlin
   *
   *  This library 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.
   *
   *  This library 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 this library; if not, write to the Free Software
   *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  /**
   * @defgroup    sys_hashes_md5 MD5
   * @ingroup     sys_hashes
   * @brief       Implementation of the MD5 hashing function
   *
   *  None of this will make any sense unless you're studying RFC 1321 as you
   *  read the code.
   *
   *  There are three primary motivations for this particular implementation.
   *  1) Programmer's pride.  I wanted to be able to say I'd done it, and I
   *     wanted to learn from the experience.
   *  2) Portability.  I wanted an implementation that I knew to be portable
   *     to a reasonable number of platforms.  In particular, the algorithm is
   *     designed with little-endian platforms in mind, but I wanted an
   *     endian-agnostic implementation.
   *  3) Compactness.  While not an overriding goal, I thought it worth-while
   *     to see if I could reduce the overall size of the result.  This is in
   *     keeping with my hopes that this library will be suitable for use in
   *     some embedded environments.
   *  Beyond that, cleanliness and clarity are always worth pursuing.
   *
   *  As mentioned above, the code really only makes sense if you are familiar
   *  with the MD5 algorithm or are using RFC 1321 as a guide.  This code is
   *  quirky, however, so you'll want to be reading carefully.
   *
   * @{
   *
   * @file
   * @brief       MD5 interface definition
   *
   * @author      Christopher R. Hertel <crh@ubiqx.mn.org>
   * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
   */
  
  #ifndef HASHES_MD5_H
  #define HASHES_MD5_H
  
  #include <stdint.h>
  #include <string.h>
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * @brief   Length of MD5 digests in byte
   */
  #define MD5_DIGEST_LENGTH           (16U)
  
  /**
   * @brief   MD5 calculation context
   */
  typedef struct {
      uint32_t len;       /**< overall number of bytes processed */
      uint32_t abcd[4];   /**< virtual registers for hash calculation */
      int b_used;         /**< number of bytes used in the current block */
      uint8_t block[64];  /**< one block is calculated at a time */
  } md5_ctx_t;
  
  /**
   * @brief   Initialize the MD5 calculation context
   *
   * @param[out] ctx      Pointer to the context to be initialized
   *
   * The purpose of the context is to make it possible to generate an MD5 Message
   * Digest in stages, rather than having to pass a single large block to a single
   * MD5 function. The context structure keeps track of various bits of state
   * information.
   *
   * Once the context is initialized, the blocks of message data are passed to the
   * <md5_update()> function. Once the final bit of data has been handed to
   * <md5_update()> the context can be closed out by calling <md5_final()>, which
   * also calculates the final MD5 result. Don't forget to free an allocated
   * context structure when you've finished using it.
   */
  void md5_init(md5_ctx_t *ctx);
  
  /**
   * @brief   Build an MD5 Message Digest within the given context
   *
   * @param[in,out] ctx   Context of the current calculation
   * @param[in] data      Input data
   * @param[in] len       Length of @p data
   */
  void md5_update(md5_ctx_t *ctx, const void *data, size_t len);
  
  /**
   * @brief   Finish up the current MD5 hash calculation generate the final hash
   *
   * @param[in] ctx       Context of the current calculation
   * @param[out] digest   Result location, must be 16 byte
   */
  void md5_final(md5_ctx_t *ctx, void *digest);
  
  /**
   * @brief   Calculate a MD5 hash from the given data
   *
   * @param[out] digest Result location, must be 16 byte
   * @param[in] data    Input data
   * @param[in] len     Length of @p src
   */
  void md5(void *digest, const void *data, size_t len);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* HASHES_MD5_H */
  /** @} */