src/libstrongswan/crypto/hmac.h

   1 /**
   2  * @file hmac.h
   3  *
   4  * @brief Interface of hmac_t.
   5  */
   6
   7 /*
   8  * Copyright (C) 2005-2006 Martin Willi
   9  * Copyright (C) 2005 Jan Hutter
  10  * Hochschule fuer Technik Rapperswil
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms of the GNU General Public License as published by the
  14  * Free Software Foundation; either version 2 of the License, or (at your
  15  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  19  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  20  * for more details.
  21  */
  22
  23 #ifndef HMAC_H_
  24 #define HMAC_H_
  25
  26 typedef struct hmac_t hmac_t;
  27
  28 #include <crypto/hashers/hasher.h>
  29
  30 /**
  31  * @brief Message authentication using hash functions.
  32  *
  33  * This class implements the message authenticaion algorithm
  34  * described in RFC2104. It uses a hash function, wich must
  35  * be implemented as a hasher_t class.
  36  *
  37  * See http://www.faqs.org/rfcs/rfc2104.html for RFC.
  38  * @see
  39  *                      - hasher_t
  40  *                      - prf_hmac_t
  41  *
  42  * @b Constructors:
  43  *  - hmac_create()
  44  *
  45  * @ingroup transforms
  46  */
  47 struct hmac_t {
  48         /**
  49          * @brief Generate message authentication code.
  50          *
  51          * If buffer is NULL, no result is given back. A next call will
  52          * append the data to already supplied data. If buffer is not NULL,
  53          * the mac of all apended data is calculated, returned and the
  54          * state of the hmac_t is reseted.
  55          *
  56          * @param this                  calling object
  57          * @param data                  chunk of data to authenticate
  58          * @param[out] buffer   pointer where the generated bytes will be written
  59          */
  60         void (*get_mac) (hmac_t *this, chunk_t data, u_int8_t *buffer);
  61
  62         /**
  63          * @brief Generates message authentication code and
  64          * allocate space for them.
  65          *
  66          * If chunk is NULL, no result is given back. A next call will
  67          * append the data to already supplied. If chunk is not NULL,
  68          * the mac of all apended data is calculated, returned and the
  69          * state of the hmac_t reset;
  70          *
  71          * @param this                  calling object
  72          * @param data                  chunk of data to authenticate
  73          * @param[out] chunk    chunk which will hold generated bytes
  74          */
  75         void (*allocate_mac) (hmac_t *this, chunk_t data, chunk_t *chunk);
  76
  77         /**
  78          * @brief Get the block size of this hmac_t object.
  79          *
  80          * @param this                  calling object
  81          * @return                              block size in bytes
  82          */
  83         size_t (*get_block_size) (hmac_t *this);
  84
  85         /**
  86          * @brief Set the key for this hmac_t object.
  87          *
  88          * Any key length is accepted.
  89          *
  90          * @param this                  calling object
  91          * @param key                   key to set
  92          */
  93         void (*set_key) (hmac_t *this, chunk_t key);
  94
  95         /**
  96          * @brief Destroys a hmac_t object.
  97          *
  98          * @param this                  calling object
  99          */
 100         void (*destroy) (hmac_t *this);
 101 };
 102
 103 /**
 104  * @brief Creates a new hmac_t object.
 105  *
 106  * Creates a hasher_t object internally.
 107  *
 108  * @param hash_algorithm                hash algorithm to use
 109  * @return
 110  *                                                              - hmac_t object
 111  *                                                              - NULL if hash algorithm is not supported
 112  *
 113  * @ingroup transforms
 114  */
 115 hmac_t *hmac_create(hash_algorithm_t hash_algorithm);
 116
 117 #endif /*HMAC_H_*/