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comparison libtommath/bn_mp_rand.c @ 284:eed26cff980b

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propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583) to branch 'au.asn.ucc.matt.dropbear' (head fff0894a0399405a9410ea1c6d118f342cf2aa64)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:49 +0000
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children 5ff8218bcee9
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283:bd240aa12ba7 284:eed26cff980b
1 #include <tommath.h>
2 #ifdef BN_MP_RAND_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
4 *
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
7 *
8 * The library was designed directly after the MPI library by
9 * Michael Fromberger but has been written from scratch with
10 * additional optimizations in place.
11 *
12 * The library is free for all purposes without any express
13 * guarantee it works.
14 *
15 * Tom St Denis, [email protected], http://math.libtomcrypt.org
16 */
17
18 /* makes a pseudo-random int of a given size */
19 int
20 mp_rand (mp_int * a, int digits)
21 {
22 int res;
23 mp_digit d;
24
25 mp_zero (a);
26 if (digits <= 0) {
27 return MP_OKAY;
28 }
29
30 /* first place a random non-zero digit */
31 do {
32 d = ((mp_digit) abs (rand ())) & MP_MASK;
33 } while (d == 0);
34
35 if ((res = mp_add_d (a, d, a)) != MP_OKAY) {
36 return res;
37 }
38
39 while (--digits > 0) {
40 if ((res = mp_lshd (a, 1)) != MP_OKAY) {
41 return res;
42 }
43
44 if ((res = mp_add_d (a, ((mp_digit) abs (rand ())), a)) != MP_OKAY) {
45 return res;
46 }
47 }
48
49 return MP_OKAY;
50 }
51 #endif