knuth-lfib.h

/* knuth-lfib.h
 *
 * A "lagged fibonacci" pseudorandomness generator.
 *
 * Described in Knuth, TAOCP, 3.6
 */

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2002 Niels Mller
 *  
 * 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., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/* NOTE: This generator is totally inappropriate for cryptographic
 * applications. It is useful for generating deterministic but
 * random-looking test data, and is used by the Nettle testsuite. */
#ifndef NETTLE_KNUTH_LFIB_H_INCLUDED
#define NETTLE_KNUTH_LFIB_H_INCLUDED

#include <inttypes.h>

#define _KNUTH_LFIB_KK 100

struct knuth_lfib_ctx
{
  uint32_t x[_KNUTH_LFIB_KK];
  unsigned index;
};

void
knuth_lfib_init(struct knuth_lfib_ctx *ctx, uint32_t seed);

/* Get's a single number in the range 0 ... 2^30-1 */
uint32_t
knuth_lfib_get(struct knuth_lfib_ctx *ctx);

/* Get an array of numbers */
void
knuth_lfib_get_array(struct knuth_lfib_ctx *ctx,
		     unsigned n, uint32_t *a);

/* Get an array of octets. */
void
knuth_lfib_random(struct knuth_lfib_ctx *ctx,
		  unsigned n, uint8_t *dst);

#endif /* NETTLE_KNUTH_LFIB_H_INCLUDED */