diff options
Diffstat (limited to 'libtommath/bn_mp_rand.c')
| -rw-r--r-- | libtommath/bn_mp_rand.c | 35 |
1 files changed, 30 insertions, 5 deletions
diff --git a/libtommath/bn_mp_rand.c b/libtommath/bn_mp_rand.c index 4c9610d..93e255a 100644 --- a/libtommath/bn_mp_rand.c +++ b/libtommath/bn_mp_rand.c @@ -15,7 +15,32 @@ * 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 (MP_GEN_RANDOM())) & 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 (MP_GEN_RANDOM())), a)) != MP_OKAY) { + if ((res = mp_add_d (a, s_gen_random(), a)) != MP_OKAY) { return res; } } @@ -50,6 +75,6 @@ mp_rand (mp_int * a, int digits) } #endif -/* $Source$ */ -/* $Revision$ */ -/* $Date$ */ +/* ref: $Format:%D$ */ +/* git commit: $Format:%H$ */ +/* commit time: $Format:%ai$ */ |