diff options
author | Shane Lontis <shane.lontis@oracle.com> | 2018-06-21 13:37:52 +1000 |
---|---|---|
committer | Pauli <paul.dale@oracle.com> | 2018-06-22 07:07:20 +1000 |
commit | 7d79d13a564d5c065318aa47f4cd511eece449e8 (patch) | |
tree | 977185435600f278fdb703f43f49ae2035437ed7 /crypto/bn/bn_prime.c | |
parent | b8c32081e02b7008a90d878eccce46da256dfe86 (diff) |
Fixed range of random produced in BN_is_prime_fasttest_ex() to be 1 < rand < w-1. It was using 1<= rand < w (which is wrong by 1 on both ends)
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6547)
Diffstat (limited to 'crypto/bn/bn_prime.c')
-rw-r--r-- | crypto/bn/bn_prime.c | 28 |
1 files changed, 13 insertions, 15 deletions
diff --git a/crypto/bn/bn_prime.c b/crypto/bn/bn_prime.c index 03ccde9510..b91b31b1f3 100644 --- a/crypto/bn/bn_prime.c +++ b/crypto/bn/bn_prime.c @@ -154,19 +154,21 @@ int BN_is_prime_fasttest_ex(const BIGNUM *a, int checks, BN_CTX *ctx_passed, int i, j, ret = -1; int k; BN_CTX *ctx = NULL; - BIGNUM *A1, *A1_odd, *check; /* taken from ctx */ + BIGNUM *A1, *A1_odd, *A3, *check; /* taken from ctx */ BN_MONT_CTX *mont = NULL; - if (BN_cmp(a, BN_value_one()) <= 0) + /* Take care of the really small primes 2 & 3 */ + if (BN_is_word(a, 2) || BN_is_word(a, 3)) + return 1; + + /* Check odd and bigger than 1 */ + if (!BN_is_odd(a) || BN_cmp(a, BN_value_one()) <= 0) return 0; if (checks == BN_prime_checks) checks = BN_prime_checks_for_size(BN_num_bits(a)); /* first look for small factors */ - if (!BN_is_odd(a)) - /* a is even => a is prime if and only if a == 2 */ - return BN_is_word(a, 2); if (do_trial_division) { for (i = 1; i < NUMPRIMES; i++) { BN_ULONG mod = BN_mod_word(a, primes[i]); @@ -186,20 +188,18 @@ int BN_is_prime_fasttest_ex(const BIGNUM *a, int checks, BN_CTX *ctx_passed, BN_CTX_start(ctx); A1 = BN_CTX_get(ctx); + A3 = BN_CTX_get(ctx); A1_odd = BN_CTX_get(ctx); check = BN_CTX_get(ctx); if (check == NULL) goto err; /* compute A1 := a - 1 */ - if (!BN_copy(A1, a)) - goto err; - if (!BN_sub_word(A1, 1)) + if (!BN_copy(A1, a) || !BN_sub_word(A1, 1)) goto err; - if (BN_is_zero(A1)) { - ret = 0; + /* compute A3 := a - 3 */ + if (!BN_copy(A3, a) || !BN_sub_word(A3, 3)) goto err; - } /* write A1 as A1_odd * 2^k */ k = 1; @@ -216,11 +216,9 @@ int BN_is_prime_fasttest_ex(const BIGNUM *a, int checks, BN_CTX *ctx_passed, goto err; for (i = 0; i < checks; i++) { - if (!BN_priv_rand_range(check, A1)) - goto err; - if (!BN_add_word(check, 1)) + /* 1 < check < a-1 */ + if (!BN_priv_rand_range(check, A3) || !BN_add_word(check, 2)) goto err; - /* now 1 <= check < a */ j = witness(check, a, A1, A1_odd, k, ctx, mont); if (j == -1) |