=pod =head1 NAME DSA_generate_parameters_ex, DSA_generate_parameters - generate DSA parameters =head1 SYNOPSIS #include <openssl/dsa.h> int DSA_generate_parameters_ex(DSA *dsa, int bits, const unsigned char *seed, int seed_len, int *counter_ret, unsigned long *h_ret, BN_GENCB *cb); Deprecated: #if OPENSSL_API_COMPAT < 0x00908000L DSA *DSA_generate_parameters(int bits, unsigned char *seed, int seed_len, int *counter_ret, unsigned long *h_ret, void (*callback)(int, int, void *), void *cb_arg); #endif =head1 DESCRIPTION DSA_generate_parameters_ex() generates primes p and q and a generator g for use in the DSA and stores the result in B<dsa>. B<bits> is the length of the prime p to be generated. For lengths under 2048 bits, the length of q is 160 bits; for lengths greater than or equal to 2048 bits, the length of q is set to 256 bits. If B<seed> is NULL, the primes will be generated at random. If B<seed_len> is less than the length of q, an error is returned. DSA_generate_parameters_ex() places the iteration count in *B<counter_ret> and a counter used for finding a generator in *B<h_ret>, unless these are B<NULL>. A callback function may be used to provide feedback about the progress of the key generation. If B<cb> is not B<NULL>, it will be called as shown below. For information on the BN_GENCB structure and the BN_GENCB_call function discussed below, refer to L<BN_generate_prime(3)>. =over 4 =item * When a candidate for q is generated, B<BN_GENCB_call(cb, 0, m++)> is called (m is 0 for the first candidate). =item * When a candidate for q has passed a test by trial division, B<BN_GENCB_call(cb, 1, -1)> is called. While a candidate for q is tested by Miller-Rabin primality tests, B<BN_GENCB_call(cb, 1, i)> is called in the outer loop (once for each witness that confirms that the candidate may be prime); i is the loop counter (starting at 0). =item * When a prime q has been found, B<BN_GENCB_call(cb, 2, 0)> and B<BN_GENCB_call(cb, 3, 0)> are called. =item * Before a candidate for p (other than the first) is generated and tested, B<BN_GENCB_call(cb, 0, counter)> is called. =item * When a candidate for p has passed the test by trial division, B<BN_GENCB_call(cb, 1, -1)> is called. While it is tested by the Miller-Rabin primality test, B<BN_GENCB_call(cb, 1, i)> is called in the outer loop (once for each witness that confirms that the candidate may be prime). i is the loop counter (starting at 0). =item * When p has been found, B<BN_GENCB_call(cb, 2, 1)> is called. =item * When the generator has been found, B<BN_GENCB_call(cb, 3, 1)> is called. =back DSA_generate_parameters() (deprecated) works in much the same way as for DSA_generate_parameters_ex, except that no B<dsa> parameter is passed and instead a newly allocated B<DSA> structure is returned. Additionally "old style" callbacks are used instead of the newer BN_GENCB based approach. Refer to L<BN_generate_prime(3)> for further information. =head1 RETURN VALUE DSA_generate_parameters_ex() returns a 1 on success, or 0 otherwise. DSA_generate_parameters() returns a pointer to the DSA structure, or B<NULL> if the parameter generation fails. The error codes can be obtained by L<ERR_get_error(3)>. =head1 BUGS Seed lengths E<gt> 20 are not supported. =head1 SEE ALSO L<DSA_new(3)>, L<ERR_get_error(3)>, L<RAND_bytes(3)>, L<DSA_free(3)>, L<BN_generate_prime(3)> =head1 COPYRIGHT Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at L<https://www.openssl.org/source/license.html>. =cut