comparison bn_mp_rand.c @ 1:22d5cf7d4b1a libtommath

Renaming branch
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:23:46 +0000
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children d29b64170cf0
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-1:000000000000 1:22d5cf7d4b1a
1 /* LibTomMath, multiple-precision integer library -- Tom St Denis
2 *
3 * LibTomMath is a library that provides multiple-precision
4 * integer arithmetic as well as number theoretic functionality.
5 *
6 * The library was designed directly after the MPI library by
7 * Michael Fromberger but has been written from scratch with
8 * additional optimizations in place.
9 *
10 * The library is free for all purposes without any express
11 * guarantee it works.
12 *
13 * Tom St Denis, [email protected], http://math.libtomcrypt.org
14 */
15 #include <tommath.h>
16
17 /* makes a pseudo-random int of a given size */
18 int
19 mp_rand (mp_int * a, int digits)
20 {
21 int res;
22 mp_digit d;
23
24 mp_zero (a);
25 if (digits <= 0) {
26 return MP_OKAY;
27 }
28
29 /* first place a random non-zero digit */
30 do {
31 d = ((mp_digit) abs (rand ()));
32 } while (d == 0);
33
34 if ((res = mp_add_d (a, d, a)) != MP_OKAY) {
35 return res;
36 }
37
38 while (digits-- > 0) {
39 if ((res = mp_lshd (a, 1)) != MP_OKAY) {
40 return res;
41 }
42
43 if ((res = mp_add_d (a, ((mp_digit) abs (rand ())), a)) != MP_OKAY) {
44 return res;
45 }
46 }
47
48 return MP_OKAY;
49 }