salsa20.h 2.74 KB
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/* salsa20.h
 *
 * The Salsa20 stream cipher.
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2012 Simon Josefsson
 * Copyright (C) 2001 Niels Möller
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 *
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 * 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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 *
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 * 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.
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 *
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 * 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
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 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02111-1301, USA.
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 */
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#ifndef NETTLE_SALSA20_H_INCLUDED
#define NETTLE_SALSA20_H_INCLUDED

#include "nettle-types.h"

#ifdef __cplusplus
extern "C" {
#endif

/* Name mangling */
#define salsa20_set_key nettle_salsa20_set_key
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#define salsa20_128_set_key nettle_salsa20_128_set_key
#define salsa20_256_set_key nettle_salsa20_256_set_key
#define salsa20_set_nonce nettle_salsa20_set_nonce
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#define salsa20_crypt nettle_salsa20_crypt
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#define _salsa20_core _nettle_salsa20_core
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#define salsa20r12_crypt nettle_salsa20r12_crypt

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/* Alias for backwards compatibility */
#define salsa20_set_iv nettle_salsa20_set_nonce

/* In octets.*/
#define SALSA20_128_KEY_SIZE 16
#define SALSA20_256_KEY_SIZE 32
#define SALSA20_BLOCK_SIZE 64
#define SALSA20_IV_SIZE 8

/* Aliases */
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#define SALSA20_MIN_KEY_SIZE 16
#define SALSA20_MAX_KEY_SIZE 32
#define SALSA20_KEY_SIZE 32

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#define _SALSA20_INPUT_LENGTH 16

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struct salsa20_ctx
{
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  /* Indices 1-4 and 11-14 holds the key (two identical copies for the
     shorter key size), indices 0, 5, 10, 15 are constant, indices 6, 7
     are the IV, and indices 8, 9 are the block counter:

     C K K K
     K C I I
     B B C K
     K K K C
  */
  uint32_t input[_SALSA20_INPUT_LENGTH];
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};

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void
salsa20_128_set_key(struct salsa20_ctx *ctx, const uint8_t *key);
void
salsa20_256_set_key(struct salsa20_ctx *ctx, const uint8_t *key);

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void
salsa20_set_key(struct salsa20_ctx *ctx,
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		size_t length, const uint8_t *key);
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void
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salsa20_set_iv(struct salsa20_ctx *ctx, const uint8_t *iv);
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void
salsa20_crypt(struct salsa20_ctx *ctx,
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	      size_t length, uint8_t *dst,
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	      const uint8_t *src);

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void
salsa20r12_crypt(struct salsa20_ctx *ctx,
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		 size_t length, uint8_t *dst,
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		 const uint8_t *src);
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void
_salsa20_core(uint32_t *dst, const uint32_t *src, unsigned rounds);

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#ifdef __cplusplus
}
#endif

#endif /* NETTLE_SALSA20_H_INCLUDED */