5 DSA_generate_parameters_ex, DSA_generate_parameters - generate DSA parameters
9 #include <openssl/dsa.h>
11 int DSA_generate_parameters_ex(DSA *dsa, int bits,
12 const unsigned char *seed,int seed_len,
13 int *counter_ret, unsigned long *h_ret, BN_GENCB *cb);
17 DSA *DSA_generate_parameters(int bits, unsigned char *seed,
18 int seed_len, int *counter_ret, unsigned long *h_ret,
19 void (*callback)(int, int, void *), void *cb_arg);
23 DSA_generate_parameters_ex() generates primes p and q and a generator g
24 for use in the DSA and stores the result in B<dsa>.
26 B<bits> is the length of the prime p to be generated.
27 For lengths under 2048 bits, the length of q is 160 bits; for lengths
28 greater than or equal to 2048 bits, the length of q is set to 256 bits.
30 If B<seed> is NULL, the primes will be generated at random.
31 If B<seed_len> is less than the length of q, an error is returned.
33 DSA_generate_parameters_ex() places the iteration count in
34 *B<counter_ret> and a counter used for finding a generator in
35 *B<h_ret>, unless these are B<NULL>.
37 A callback function may be used to provide feedback about the progress
38 of the key generation. If B<cb> is not B<NULL>, it will be
39 called as shown below. For information on the BN_GENCB structure and the
40 BN_GENCB_call function discussed below, refer to
41 L<BN_generate_prime(3)>.
47 When a candidate for q is generated, B<BN_GENCB_call(cb, 0, m++)> is called
48 (m is 0 for the first candidate).
52 When a candidate for q has passed a test by trial division,
53 B<BN_GENCB_call(cb, 1, -1)> is called.
54 While a candidate for q is tested by Miller-Rabin primality tests,
55 B<BN_GENCB_call(cb, 1, i)> is called in the outer loop
56 (once for each witness that confirms that the candidate may be prime);
57 i is the loop counter (starting at 0).
61 When a prime q has been found, B<BN_GENCB_call(cb, 2, 0)> and
62 B<BN_GENCB_call(cb, 3, 0)> are called.
66 Before a candidate for p (other than the first) is generated and tested,
67 B<BN_GENCB_call(cb, 0, counter)> is called.
71 When a candidate for p has passed the test by trial division,
72 B<BN_GENCB_call(cb, 1, -1)> is called.
73 While it is tested by the Miller-Rabin primality test,
74 B<BN_GENCB_call(cb, 1, i)> is called in the outer loop
75 (once for each witness that confirms that the candidate may be prime).
76 i is the loop counter (starting at 0).
80 When p has been found, B<BN_GENCB_call(cb, 2, 1)> is called.
84 When the generator has been found, B<BN_GENCB_call(cb, 3, 1)> is called.
88 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
89 instead a newly allocated B<DSA> structure is returned. Additionally "old
90 style" callbacks are used instead of the newer BN_GENCB based approach.
91 Refer to L<BN_generate_prime(3)> for further information.
95 DSA_generate_parameters_ex() returns a 1 on success, or 0 otherwise.
97 DSA_generate_parameters() returns a pointer to the DSA structure, or
98 B<NULL> if the parameter generation fails.
100 The error codes can be obtained by L<ERR_get_error(3)>.
104 Seed lengths E<gt> 20 are not supported.
108 L<dsa(3)>, L<ERR_get_error(3)>, L<rand(3)>,
109 L<DSA_free(3)>, L<BN_generate_prime(3)>