diff options
Diffstat (limited to 'libtommath/bn_mp_rand.c')
| -rw-r--r-- | libtommath/bn_mp_rand.c | 96 |
1 files changed, 31 insertions, 65 deletions
diff --git a/libtommath/bn_mp_rand.c b/libtommath/bn_mp_rand.c index 93e255a..7e9052c 100644 --- a/libtommath/bn_mp_rand.c +++ b/libtommath/bn_mp_rand.c @@ -1,80 +1,46 @@ -#include <tommath_private.h> +#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 - */ +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ -#if MP_GEN_RANDOM_MAX == 0xffffffff - #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 +mp_err(*s_mp_rand_source)(void *out, size_t size) = s_mp_rand_platform; -/* makes a pseudo-random int of a given size */ -static mp_digit s_gen_random(void) +void mp_rand_source(mp_err(*source)(void *out, size_t size)) { - 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; + s_mp_rand_source = (source == NULL) ? s_mp_rand_platform : source; } -int -mp_rand (mp_int * a, int digits) +mp_err mp_rand(mp_int *a, int digits) { - int res; - mp_digit d; + int i; + mp_err err; + + mp_zero(a); - mp_zero (a); - if (digits <= 0) { - return MP_OKAY; - } + if (digits <= 0) { + return MP_OKAY; + } - /* first place a random non-zero digit */ - do { - d = s_gen_random(); - } while (d == 0); + if ((err = mp_grow(a, digits)) != MP_OKAY) { + return err; + } - if ((res = mp_add_d (a, d, a)) != MP_OKAY) { - return res; - } + if ((err = s_mp_rand_source(a->dp, (size_t)digits * sizeof(mp_digit))) != MP_OKAY) { + return err; + } - while (--digits > 0) { - if ((res = mp_lshd (a, 1)) != MP_OKAY) { - return res; - } + /* TODO: We ensure that the highest digit is nonzero. Should this be removed? */ + while ((a->dp[digits - 1] & MP_MASK) == 0u) { + if ((err = s_mp_rand_source(a->dp + digits - 1, sizeof(mp_digit))) != MP_OKAY) { + return err; + } + } - if ((res = mp_add_d (a, s_gen_random(), a)) != MP_OKAY) { - return res; - } - } + a->used = digits; + for (i = 0; i < digits; ++i) { + a->dp[i] &= MP_MASK; + } - return MP_OKAY; + return MP_OKAY; } #endif - -/* ref: $Format:%D$ */ -/* git commit: $Format:%H$ */ -/* commit time: $Format:%ai$ */ |