|
282
|
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 * |
|
386
|
15 * Tom St Denis, [email protected], http://math.libtomcrypt.com |
|
282
|
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 |
|
386
|
52 |
|
|
53 /* $Source: /cvs/libtom/libtommath/bn_mp_rand.c,v $ */ |
|
|
54 /* $Revision: 1.3 $ */ |
|
|
55 /* $Date: 2006/03/31 14:18:44 $ */ |
