bn_mp_rand.c
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#include <tommath.h>
#ifdef BN_MP_RAND_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
* LibTomMath is a library that provides multiple-precision
* integer arithmetic as well as number theoretic functionality.
*
* The library was designed directly after the MPI library by
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
*/
/* makes a pseudo-random int of a given size */
int
mp_rand (mp_int * a, int digits)
{
int res;
mp_digit d;
mp_zero (a);
if (digits <= 0) {
return MP_OKAY;
}
/* first place a random non-zero digit */
do {
d = ((mp_digit) abs (rand ())) & MP_MASK;
} while (d == 0);
if ((res = mp_add_d (a, d, a)) != MP_OKAY) {
return res;
}
while (--digits > 0) {
if ((res = mp_lshd (a, 1)) != MP_OKAY) {
return res;
}
if ((res = mp_add_d (a, ((mp_digit) abs (rand ())), a)) != MP_OKAY) {
return res;
}
}
return MP_OKAY;
}
#endif
/* $Source: /cvs/libtom/libtommath/bn_mp_rand.c,v $ */
/* $Revision: 1.3 $ */
/* $Date: 2006/03/31 14:18:44 $ */