serpent.h 2.38 KB
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/* serpent.h
 *
 * The serpent block cipher.
 */

/* 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.
 * 
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 * The nettle library is distributed in the hope that it will be useful, but
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 * 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
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 * along with the nettle library; see the file COPYING.LIB.  If not, write to
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 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/* Serpent is a 128-bit block cipher that accepts a key size of 256
 * bits, designed by Ross Anderson, Eli Biham, and Lars Knudsen. See
 * http://www.cl.cam.ac.uk/~rja14/serpent.html for details.
 */

#ifndef NETTLE_SERPENT_H_INCLUDED
#define NETTLE_SERPENT_H_INCLUDED

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#include "nettle-types.h"
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#ifdef __cplusplus
extern "C" {
#endif

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/* Name mangling */
#define serpent_set_key nettle_serpent_set_key
#define serpent_encrypt nettle_serpent_encrypt
#define serpent_decrypt nettle_serpent_decrypt

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#define SERPENT_BLOCK_SIZE 16
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/* Other key lengths are possible, but the design of Serpent makes
 * smaller key lengths quite pointless; they cheated with the AES
 * requirements, using a 256-bit key length exclusively and just
 * padding it out if the desired key length was less, so there really
 * is no advantage to using key lengths less than 256 bits. */
#define SERPENT_KEY_SIZE 32
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/* Allow keys of size 128 <= bits <= 256 */

#define SERPENT_MIN_KEY_SIZE 16
#define SERPENT_MAX_KEY_SIZE 32

struct serpent_ctx
{
  uint32_t keys[33][4];  /* key schedule */
};

void
serpent_set_key(struct serpent_ctx *ctx,
                unsigned length, const uint8_t *key);

void
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serpent_encrypt(const struct serpent_ctx *ctx,
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                unsigned length, uint8_t *dst,
                const uint8_t *src);
void
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serpent_decrypt(const struct serpent_ctx *ctx,
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                unsigned length, uint8_t *dst,
                const uint8_t *src);

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#ifdef __cplusplus
}
#endif

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#endif /* NETTLE_SERPENT_H_INCLUDED */