blob: 2ed665eb7e051fdb51bb8017d11510ed46ae3824 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
|
#include <tommath_private.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, tstdenis82@gmail.com, http://libtom.org
*/
#if defined(MP_8BIT) || defined(MP_16BIT)
#define MP_GEN_RANDOM_SHIFT DIGIT_BIT
#else
#if MP_GEN_RANDOM_MAX == 0xffffffffu
#define MP_GEN_RANDOM_SHIFT 32
#elif MP_GEN_RANDOM_MAX == 32767
/* SHRT_MAX */
#define MP_GEN_RANDOM_SHIFT 15
#elif MP_GEN_RANDOM_MAX == 2147483647
/* INT_MAX */
#define MP_GEN_RANDOM_SHIFT 31
#elif !defined(MP_GEN_RANDOM_SHIFT)
#error Thou shalt define their own valid MP_GEN_RANDOM_SHIFT
#endif
#endif
/* makes a pseudo-random int of a given size */
static mp_digit s_gen_random(void)
{
mp_digit d = 0, msk = 0;
do {
d <<= MP_GEN_RANDOM_SHIFT;
d |= ((mp_digit) MP_GEN_RANDOM());
msk <<= MP_GEN_RANDOM_SHIFT;
msk |= (MP_MASK & MP_GEN_RANDOM_MAX);
} while ((MP_MASK & msk) != MP_MASK);
d &= MP_MASK;
return d;
}
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 = s_gen_random();
} while (d == 0u);
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, s_gen_random(), a)) != MP_OKAY) {
return res;
}
}
return MP_OKAY;
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
|
