crypto/cbc-mac.c

   1 /* cbc-mac.c
   2  *
   3  * Cipher block chaining message authentication code.
   4  */
   5
   6 /* nettle, low-level cryptographics library
   7  *
   8  * Copyright (C) 2003 Simon Josefsson
   9  *
  10  * The nettle library is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU Lesser General Public License as published by
  12  * the Free Software Foundation; either version 2.1 of the License, or (at your
  13  * option) any later version.
  14  *
  15  * The nettle library is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  17  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  18  * License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public License
  21  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  22  * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  23  * MA 02111-1307, USA.
  24  */
  25
  26 #if HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include <assert.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33
  34 #include "cbc-mac.h"
  35
  36 #include "memxor.h"
  37
  38 void
  39 cbc_mac(void *ctx,
  40         void (*f)(void *ctx,
  41                   unsigned length, uint8_t *dst,
  42                   const uint8_t *src),
  43         unsigned block_size,
  44         uint8_t *iv,
  45         unsigned length,
  46         uint8_t *dst,
  47         const uint8_t *src)
  48 {
  49   assert(!(length % block_size));
  50
  51   for ( ; length; length -= block_size, src += block_size)
  52     {
  53       memxor(iv, src, block_size);
  54       f(ctx, block_size, dst, iv);
  55       memcpy(iv, dst, block_size);
  56     }
  57 }