diff options
-rw-r--r-- | CHANGES | 14 | ||||
-rw-r--r-- | doc/crypto/BN_generate_prime.pod | 50 |
2 files changed, 46 insertions, 18 deletions
@@ -20,11 +20,15 @@ generation becomes much faster. This implies a change for the callback functions in DSA_is_prime - and DSA_generate_parameters: They are now called once for each - positive witness in the Rabin-Miller test, not just occasionally - in the inner loop; and the parameters to the callback function now - provide an iteration count for the outer loop rather than for the - current invocation of the inner loop. + and DSA_generate_parameters: The callback function is called once + for each positive witness in the Rabin-Miller test, not just + occasionally in the inner loop; and the parameters to the + callback function now provide an iteration count for the outer + loop rather than for the current invocation of the inner loop. + DSA_generate_parameters additionally can call the callback + function with an 'iteration count' of -1, meaning that a + candidate has passed the trial division test (when q is generated + from an application-provided seed, trial division is skipped). [Bodo Moeller] *) New function BN_is_prime_fasttest that optionally does trial diff --git a/doc/crypto/BN_generate_prime.pod b/doc/crypto/BN_generate_prime.pod index 3cd239e893..ff32b10676 100644 --- a/doc/crypto/BN_generate_prime.pod +++ b/doc/crypto/BN_generate_prime.pod @@ -2,7 +2,7 @@ =head1 NAME -BN_generate_prime, BN_is_prime - Generate primes and test for primality +BN_generate_prime, BN_is_prime, BN_is_prime_fasttest - Generate primes and test for primality =head1 SYNOPSIS @@ -14,11 +14,14 @@ BN_generate_prime, BN_is_prime - Generate primes and test for primality int BN_is_prime(BIGNUM *a, int checks, void (*callback)(int, int, void *), BN_CTX *ctx, void *cb_arg); + int BN_is_prime_fasttest(BIGNUM *a, int checks, void (*callback)(int, int, + void *), BN_CTX *ctx, BN_CTX *ctx2, void *cb_arg, int do_trial_division); + =head1 DESCRIPTION BN_generate_prime() generates a pseudo-random prime number of B<num> bits. -If B<ret> is not NULL, it will be used to store the number. +If B<ret> is not B<NULL>, it will be used to store the number. If B<callback> is not B<NULL>, it is called as follows: @@ -43,8 +46,8 @@ When a prime has been found, B<callback(2, i, cb_arg)> is called. The prime may have to fulfill additional requirements for use in Diffie-Hellman key exchange: -If B<add> is not NULL, the prime will fulfill the condition p % B<add> -== B<rem> (p % B<add> == 1 if B<rem> == NULL) in order to suit a given +If B<add> is not B<NULL>, the prime will fulfill the condition p % B<add> +== B<rem> (p % B<add> == 1 if B<rem> == B<NULL>) in order to suit a given generator. If B<safe> is true, it will be a safe prime (i.e. a prime p so @@ -53,20 +56,40 @@ that (p-1)/2 is also prime). The PRNG must be seeded prior to calling BN_generate_prime(). The prime number generation has a negligible error probability. -BN_is_prime() tests if the number B<a> is prime. This is done by -performing a Miller-Rabin probabilistic primality test with B<checks> -iterations. If B<checks == BN_prime_check>, it uses a number -of iterations that yields a false positive rate of at most 2^-80 for -random input. +BN_is_prime() and BN_is_prime_fasttest test if the number B<a> is +prime. The following tests are performed until one of them shows that +B<a> is composite; if B<a> passes all these tests, it is considered +prime. + +=over 4 + +=item * + +BN_is_prime_fasttest(), when called with B<do_trial_division == 1>, +first attempts trial division by a number of small primes; +if no divisors are found by this test and B<callback> is not B<NULL>, +B<callback(1, -1, cb_arg)> is called. +If B<do_trial_division == 0>, this test is skipped. + +=item * + +Both BN_is_prime() and BN_is_prime_fasttest() perform a Miller-Rabin +probabilistic primality test with B<checks> iterations. If +B<checks == BN_prime_check>, a number of iterations is used that +yields a false positive rate of at most 2^-80 for random input. If B<callback> is not B<NULL>, B<callback(1, j, cb_arg)> is called -after the j-th iteration. B<ctx> is a pre-allocated B<BN_CTX> (to save -the overhead of allocating and freeing the structure in a loop), or -NULL. +after the j-th iteration (j = 0, 1, ...). B<ctx> is a +pre-allocated B<BN_CTX> (to save the overhead of allocating and +freeing the structure in a loop), or B<NULL>. For +BN_is_prime_fasttest(), B<ctx2> is a second pre-allocated B<BN_CTX> or +B<NULL> (lacking this parameter, BN_is_prime() always has to allocated +an additional B<CN_CTX>). + =head1 RETURN VALUES -BN_generate_prime() returns the prime number on success, NULL otherwise. +BN_generate_prime() returns the prime number on success, B<NULL> otherwise. BN_is_prime() returns 0 if the number is composite, 1 if it is prime with an error probability of less than 0.25^B<checks>, and @@ -83,5 +106,6 @@ L<bn(3)|bn(3)>, L<err(3)|err(3)>, L<rand(3)|rand(3)> The B<cb_arg> arguments to BN_generate_prime() and to BN_is_prime() were added in SSLeay 0.9.0. The B<ret> argument to BN_generate_prime() was added in SSLeay 0.9.1. +BN_is_prime_fasttest() was added in OpenSSL 0.9.5. =cut |