crypto/external/bsd/heimdal/dist/lib/hcrypto/libtommath/bn_mp_rand.c

   1 /*      $NetBSD: bn_mp_rand.c,v 1.1.1.2 2014/04/24 12:45:31 pettai Exp $        */
   2
   3 #include <tommath.h>
   4 #ifdef BN_MP_RAND_C
   5 /* LibTomMath, multiple-precision integer library -- Tom St Denis
   6  *
   7  * LibTomMath is a library that provides multiple-precision
   8  * integer arithmetic as well as number theoretic functionality.
   9  *
  10  * The library was designed directly after the MPI library by
  11  * Michael Fromberger but has been written from scratch with
  12  * additional optimizations in place.
  13  *
  14  * The library is free for all purposes without any express
  15  * guarantee it works.
  16  *
  17  * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
  18  */
  19
  20 /* makes a pseudo-random int of a given size */
  21 int
  22 mp_rand (mp_int * a, int digits)
  23 {
  24   int     res;
  25   mp_digit d;
  26
  27   mp_zero (a);
  28   if (digits <= 0) {
  29     return MP_OKAY;
  30   }
  31
  32   /* first place a random non-zero digit */
  33   do {
  34     d = ((mp_digit) abs (rand ())) & MP_MASK;
  35   } while (d == 0);
  36
  37   if ((res = mp_add_d (a, d, a)) != MP_OKAY) {
  38     return res;
  39   }
  40
  41   while (--digits > 0) {
  42     if ((res = mp_lshd (a, 1)) != MP_OKAY) {
  43       return res;
  44     }
  45
  46     if ((res = mp_add_d (a, ((mp_digit) abs (rand ())), a)) != MP_OKAY) {
  47       return res;
  48     }
  49   }
  50
  51   return MP_OKAY;
  52 }
  53 #endif
  54
  55 /* Source: /cvs/libtom/libtommath/bn_mp_rand.c,v  */
  56 /* Revision: 1.4  */
  57 /* Date: 2006/12/28 01:25:13  */