From 22919cd4f2d4aaa80ace75ae92b682f5ff426ec8 Mon Sep 17 00:00:00 2001
From: Steffen Jaeckel <s@jaeckel.eu>
Date: Tue, 4 Jul 2017 10:58:10 +0200
Subject: [PATCH] rand_bn_range(): count bits once

---
 src/math/rand_bn.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/math/rand_bn.c b/src/math/rand_bn.c
index a85a965..3d4f10c 100755
--- a/src/math/rand_bn.c
+++ b/src/math/rand_bn.c
@@ -55,13 +55,14 @@ cleanup:
 */
 int rand_bn_range(void *N, void *limit, prng_state *prng, int wprng)
 {
-   int res;
+   int res, bits;
 
    LTC_ARGCHK(N != NULL);
    LTC_ARGCHK(limit != NULL);
 
+   bits = mp_count_bits(limit);
    do {
-     res = rand_bn_bits(N, mp_count_bits(limit), prng, wprng);
+     res = rand_bn_bits(N, bits, prng, wprng);
      if (res != CRYPT_OK) return res;
    } while (mp_cmp_d(N, 0) != LTC_MP_GT || mp_cmp(N, limit) != LTC_MP_LT);