/src/dropbear/libtommath/bn_mp_rand.c
Line | Count | Source |
1 | | #include "tommath_private.h" |
2 | | #ifdef BN_MP_RAND_C |
3 | | /* LibTomMath, multiple-precision integer library -- Tom St Denis */ |
4 | | /* SPDX-License-Identifier: Unlicense */ |
5 | | |
6 | | /* Dropbear sets this separately, avoid platform code */ |
7 | | mp_err(*s_mp_rand_source)(void *out, size_t size) = NULL; |
8 | | |
9 | | void mp_rand_source(mp_err(*source)(void *out, size_t size)) |
10 | 36 | { |
11 | | /* Dropbear, don't reset to platform if source==NULL */ |
12 | 36 | s_mp_rand_source = source; |
13 | 36 | } |
14 | | |
15 | | mp_err mp_rand(mp_int *a, int digits) |
16 | 3.92k | { |
17 | 3.92k | int i; |
18 | 3.92k | mp_err err; |
19 | | |
20 | 3.92k | mp_zero(a); |
21 | | |
22 | 3.92k | if (digits <= 0) { |
23 | 0 | return MP_OKAY; |
24 | 0 | } |
25 | | |
26 | 3.92k | if ((err = mp_grow(a, digits)) != MP_OKAY) { |
27 | 0 | return err; |
28 | 0 | } |
29 | | |
30 | 3.92k | if ((err = s_mp_rand_source(a->dp, (size_t)digits * sizeof(mp_digit))) != MP_OKAY) { |
31 | 0 | return err; |
32 | 0 | } |
33 | | |
34 | | /* TODO: We ensure that the highest digit is nonzero. Should this be removed? */ |
35 | 3.92k | while ((a->dp[digits - 1] & MP_MASK) == 0u) { |
36 | 0 | if ((err = s_mp_rand_source(a->dp + digits - 1, sizeof(mp_digit))) != MP_OKAY) { |
37 | 0 | return err; |
38 | 0 | } |
39 | 0 | } |
40 | | |
41 | 3.92k | a->used = digits; |
42 | 8.96k | for (i = 0; i < digits; ++i) { |
43 | 5.04k | a->dp[i] &= MP_MASK; |
44 | 5.04k | } |
45 | | |
46 | 3.92k | return MP_OKAY; |
47 | 3.92k | } |
48 | | #endif |