Commit b8527e92f8401a79b86e779caaaf00dca83f73c7
2016-10-10T00:48:15
Merge branch 'fix/56' into develop This closes #56 and #57
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diff --git a/bn_mp_rand.c b/bn_mp_rand.c
index 4c9610d..fc98e52 100644
--- a/bn_mp_rand.c
+++ b/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 mp_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_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 = mp_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, mp_gen_random(), a)) != MP_OKAY) {
return res;
}
}
diff --git a/tommath.h b/tommath.h
index cec3722..b1a97af 100644
--- a/tommath.h
+++ b/tommath.h
@@ -102,8 +102,10 @@ extern "C" {
/* use arc4random on platforms that support it */
#ifdef MP_USE_ALT_RAND
#define MP_GEN_RANDOM() arc4random()
+ #define MP_GEN_RANDOM_MAX 0xffffffff
#else
#define MP_GEN_RANDOM() rand()
+ #define MP_GEN_RANDOM_MAX RAND_MAX
#endif
#define MP_DIGIT_BIT DIGIT_BIT