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/* des3.h
*
* Triple DES cipher. Three key encrypt-decrypt-encrypt.
*/
/* 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 "des.h"
/* It's possible to make some more general pipe construction, like the
* lsh/src/cascade.c, but as in practice it's never used for anything
* like triple DES, it's not worth the effort. */
/* Returns 1 for good keys and 0 for weak keys. */
int
des3_set_key(struct des3_ctx *ctx, const uint8_t *key)
{
unsigned i;
int is_good = 1;
for (i = 0; i<3; i++, key += DES_KEY_SIZE)
if (!des_set_key(&ctx->des[i], key))
is_good = 0;
return is_good;
}
void
des3_encrypt(const struct des3_ctx *ctx,
unsigned length, uint8_t *dst,
const uint8_t *src)
{
des_encrypt(&ctx->des[0],
length, dst, src);
des_decrypt(&ctx->des[1],
length, dst, dst);
des_encrypt(&ctx->des[2],
length, dst, dst);
}
void
des3_decrypt(const struct des3_ctx *ctx,
unsigned length, uint8_t *dst,
const uint8_t *src)
{
des_decrypt(&ctx->des[2],
length, dst, src);
des_encrypt(&ctx->des[1],
length, dst, dst);
des_decrypt(&ctx->des[0],
length, dst, dst);
}
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