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fix BN_rand_range

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This commit is contained in:
Bodo Möller 2001-12-14 10:09:01 +00:00
parent a69b3e94f3
commit 865ce8abcb
2 changed files with 19 additions and 11 deletions
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6
CHANGES
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@ -4,6 +4,12 @@
Changes between 0.9.6b and 0.9.6c [XX xxx XXXX] Changes between 0.9.6b and 0.9.6c [XX xxx XXXX]
*) Fix BN_rand_range bug pointed out by Dominikus Scherkl
<Dominikus.Scherkl@biodata.com>. (The previous implementation
worked incorrectly for those cases where range = 10..._2 and
3*range is two bits longer than range.)
[Bodo Moeller]
*) Only add signing time to PKCS7 structures if it is not already *) Only add signing time to PKCS7 structures if it is not already
present. present.
[Steve Henson] [Steve Henson]

24
crypto/bn/bn_rand.c
View File

@ -238,22 +238,15 @@ static int bn_rand_range(int pseudo, BIGNUM *r, BIGNUM *range)
n = BN_num_bits(range); /* n > 0 */ n = BN_num_bits(range); /* n > 0 */
/* BN_is_bit_set(range, n - 1) always holds */
if (n == 1) if (n == 1)
{ {
if (!BN_zero(r)) return 0; if (!BN_zero(r)) return 0;
} }
else if (BN_is_bit_set(range, n - 2)) else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3))
{ {
do /* range = 100..._2,
{
/* range = 11..._2, so each iteration succeeds with probability >= .75 */
if (!bn_rand(r, n, -1, 0)) return 0;
}
while (BN_cmp(r, range) >= 0);
}
else
{
/* range = 10..._2,
* so 3*range (= 11..._2) is exactly one bit longer than range */ * so 3*range (= 11..._2) is exactly one bit longer than range */
do do
{ {
@ -272,6 +265,15 @@ static int bn_rand_range(int pseudo, BIGNUM *r, BIGNUM *range)
} }
while (BN_cmp(r, range) >= 0); while (BN_cmp(r, range) >= 0);
} }
else
{
do
{
/* range = 11..._2 or range = 101..._2 */
if (!bn_rand(r, n, -1, 0)) return 0;
}
while (BN_cmp(r, range) >= 0);
}
return 1; return 1;
} }