Mercurial > dropbear
comparison bn_mp_rand.c @ 1:22d5cf7d4b1a libtommath
Renaming branch
author | Matt Johnston <matt@ucc.asn.au> |
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date | Mon, 31 May 2004 18:23:46 +0000 |
parents | |
children | d29b64170cf0 |
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-1:000000000000 | 1:22d5cf7d4b1a |
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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 } |