cbc.c

/* cbc.c
 *
 * Cipher block chaining mode.
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2001 Niels Möller
 *  
 * The nettle 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.
 * 
 * The nettle 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 the nettle library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02111-1301, USA.
 */

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <assert.h>
#include <stdlib.h>
#include <string.h>

#include "cbc.h"

#include "memxor.h"
#include "nettle-internal.h"

void
cbc_encrypt(const void *ctx, nettle_cipher_func *f,
	    size_t block_size, uint8_t *iv,
	    size_t length, uint8_t *dst,
	    const uint8_t *src)
{
  assert(!(length % block_size));

  for ( ; length; length -= block_size, src += block_size, dst += block_size)
    {
      memxor(iv, src, block_size);
      f(ctx, block_size, dst, iv);
      memcpy(iv, dst, block_size);
    }
}

/* Don't allocate any more space than this on the stack */
#define CBC_BUFFER_LIMIT 512

void
cbc_decrypt(const void *ctx, nettle_cipher_func *f,
	    size_t block_size, uint8_t *iv,
	    size_t length, uint8_t *dst,
	    const uint8_t *src)
{
  assert(!(length % block_size));

  if (!length)
    return;

  if (src != dst)
    {