Files
dropbear/bn_mp_rand.c
Matt Johnston fc43a488cc import of libtommath 0.32
--HG--
branch : libtommath-orig
extra : convert_revision : 0dc5b2d6d8c18b7e32b077cd8051bd63835afa1e
2004-12-19 11:33:56 +00:00

52 lines
1.1 KiB
C

#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@iahu.ca, http://math.libtomcrypt.org
*/
/* 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 ()));
} 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