diff options
Diffstat (limited to 'libtommath/bn_mp_rand.c')
| -rw-r--r-- | libtommath/bn_mp_rand.c | 37 |
1 files changed, 33 insertions, 4 deletions
diff --git a/libtommath/bn_mp_rand.c b/libtommath/bn_mp_rand.c index 17c1fbe..93e255a 100644 --- a/libtommath/bn_mp_rand.c +++ b/libtommath/bn_mp_rand.c @@ -1,4 +1,4 @@ -#include <tommath.h> +#include <tommath_private.h> #ifdef BN_MP_RAND_C /* LibTomMath, multiple-precision integer library -- Tom St Denis * @@ -12,10 +12,35 @@ * The library is free for all purposes without any express * guarantee it works. * - * Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com + * Tom St Denis, tstdenis82@gmail.com, http://libtom.org */ +#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 + /* 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) { @@ -29,7 +54,7 @@ mp_rand (mp_int * a, int digits) /* first place a random non-zero digit */ do { - d = ((mp_digit) abs (rand ())) & MP_MASK; + d = s_gen_random(); } while (d == 0); if ((res = mp_add_d (a, d, a)) != MP_OKAY) { @@ -41,7 +66,7 @@ mp_rand (mp_int * a, int digits) return res; } - if ((res = mp_add_d (a, ((mp_digit) abs (rand ())), a)) != MP_OKAY) { + if ((res = mp_add_d (a, s_gen_random(), a)) != MP_OKAY) { return res; } } @@ -49,3 +74,7 @@ mp_rand (mp_int * a, int digits) return MP_OKAY; } #endif + +/* ref: $Format:%D$ */ +/* git commit: $Format:%H$ */ +/* commit time: $Format:%ai$ */ |