Source/lib/crypto/hmac.h

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