Fix a bug in case the most significants bits were generated as zero.

2011-09-27 01:57:58 +02:00 · 2011-09-27 01:57:58 +02:00 · faf0f96de1
commit faf0f96de1
parent 3d5ada60c3
1 changed files with 4 additions and 0 deletions
--- a/src/numtheory/fp_prime_random_ex.c
+++ b/src/numtheory/fp_prime_random_ex.c
@ -55,6 +55,10 @@ int fp_prime_random_ex(fp_int *a, int size, int flags, tfm_prime_callback cb, vo
      /* make sure the MSbyte has the required number of bits */
      a->dp[dsize-1]    &= maskAND_msb;

+      /* Force a->used as well, it could be smaller if the highest bits were
+         generated as 0 by the callback. */
+      a->used           = dsize;
+
      /* modify the LSbyte as requested */
      a->dp[0]          |= maskOR_lsb;