gl/lib/rand-isaac.h

   1 /* Bob Jenkins's cryptographic random number generators, ISAAC and ISAAC64.
   2
   3    Copyright (C) 1999-2024 Free Software Foundation, Inc.
   4    Copyright (C) 1997, 1998, 1999 Colin Plumb.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation, either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <https://www.gnu.org/licenses/>.
  18
  19    Written by Colin Plumb and Paul Eggert.  */
  20
  21 #ifndef _GL_RAND_ISAAC_H
  22 #define _GL_RAND_ISAAC_H
  23
  24 #include <stddef.h>
  25 #include <stdint.h>
  26
  27 /* Log base 2 of the number of useful bits in an ISAAC word.  It must
  28    be either 5 or 6.  By default, this uses a value that should be
  29    faster for this architecture.  */
  30 #ifndef ISAAC_BITS_LOG
  31  #if SIZE_MAX >> 31 >> 31 < 3 /* SIZE_MAX < 2**64 - 1 */
  32   #define ISAAC_BITS_LOG 5
  33  #else
  34   #define ISAAC_BITS_LOG 6
  35  #endif
  36 #endif
  37
  38 /* The number of bits in an ISAAC word.  */
  39 #define ISAAC_BITS (1 << ISAAC_BITS_LOG)
  40
  41 #if ISAAC_BITS == 32
  42   typedef uint_least32_t isaac_word;
  43 #else
  44   typedef uint_least64_t isaac_word;
  45 #endif
  46
  47 /* Size of the state tables to use.  ISAAC_WORDS_LOG should be at least 3,
  48    and smaller values give less security.  */
  49 #define ISAAC_WORDS_LOG 8
  50 #define ISAAC_WORDS (1 << ISAAC_WORDS_LOG)
  51 #define ISAAC_BYTES (ISAAC_WORDS * sizeof (isaac_word))
  52
  53 /* State variables for the random number generator.  The M member
  54    should be seeded with nonce data before calling isaac_seed.  The
  55    other members are private.  */
  56 struct isaac_state
  57   {
  58     isaac_word m[ISAAC_WORDS];  /* Main state array */
  59     isaac_word a, b, c;         /* Extra variables */
  60   };
  61
  62 void isaac_seed (struct isaac_state *) _GL_ATTRIBUTE_NONNULL ();
  63 void isaac_refill (struct isaac_state *, isaac_word[ISAAC_WORDS])
  64   _GL_ATTRIBUTE_NONNULL ();
  65
  66 #endif