5 DSA_generate_parameters - Generate DSA parameters
9 #include <openssl/dsa.h>
11 DSA * DSA_generate_parameters(int bits, unsigned char *seed,
12 int seed_len, int *counter_ret, unsigned long *h_ret,
13 void (*callback)(), void *cb_arg);
17 DSA_generate_parameters() generates primes p and q and a generator g
20 B<bits> is the length of the prime to be generated; the DSS allows a
23 If B<seed> is B<NULL> or B<seed_len> E<lt> 20, the primes will be
24 generated at random. Otherwise, the seed is used to generate
25 them. If the given seed does not yield a prime q, a new random
26 seed is chosen and placed at B<seed>.
28 DSA_generate_parameters() places the iteration count in
29 *B<counter_ret> and a counter used for finding a generator in
30 *B<h_ret>, unless these are B<NULL>.
32 A callback function may be used to provide feedback about the progress
33 of the key generation. If B<callback> is not B<NULL>, it will be
40 When a candidate for q is generated, B<callback(0, m++, cb_arg)> is called
41 (m is 0 for the first candidate).
45 While a candidate for q is tested, B<callback(1, i, cb_arg)>
46 is called in the outer loop of the Miller-Rabin primality tests
47 (once for each witness that confirms that the candidate may be prime).
48 i is the loop counter (starting at 0).
52 When a prime q has been found, B<callback(2, 0, cb_arg)> and
53 B<callback(3, 0, cb_arg)> are called.
57 Before a candidate for p (other than the first) is generated and tested,
58 B<callback(0, counter, cb_arg)> is called.
62 While a candidate for p is tested, B<callback(1, j++, cb_arg)>
63 is called in the outer loop of the Miller-Rabin primality test
64 (once for each witness that confirms that the candidate may be prime).
65 i is the loop counter (starting at 0).
69 When p has been found, B<callback(2, 1, cb_arg)> is called.
73 When the generator has been found, B<callback(3, 1, cb_arg)> is called.
79 DSA_generate_parameters() returns a pointer to the DSA structure, or
80 B<NULL> if the parameter generation fails. The error codes can be
81 obtained by L<ERR_get_error(3)|ERR_get_error(3)>.
85 Seed lengths E<gt> 20 are not supported.
89 L<dsa(3)|dsa(3)>, L<err(3)|err(3)>, L<rand(3)|rand(3)>,
90 L<DSA_free(3)|DSA_free(3)>
94 DSA_generate_parameters() appeared in SSLeay 0.8. The B<cb_arg>
95 argument was added in SSLeay 0.9.0.
96 In versions up to OpenSSL 0.9.4, B<callback(1, ...)> was called
97 in the inner loop of the Miller-Rabin test whenever it reached the
98 squaring step (the parameters to B<callback> did not reveal how many
99 witnesses had been tested); since OpenSSL 0.9.5, B<callback(1, ...)>
100 is called as in BN_is_prime(3), i.e. once for each witness.