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 #if OPENSSL_API_COMPAT < 0x00908000L
18 DSA *DSA_generate_parameters(int bits, unsigned char *seed,
19 int seed_len, int *counter_ret, unsigned long *h_ret,
20 void (*callback)(int, int, void *), void *cb_arg);
25 DSA_generate_parameters_ex() generates primes p and q and a generator g
26 for use in the DSA and stores the result in B<dsa>.
28 B<bits> is the length of the prime p to be generated.
29 For lengths under 2048 bits, the length of q is 160 bits; for lengths
30 greater than or equal to 2048 bits, the length of q is set to 256 bits.
32 If B<seed> is NULL, the primes will be generated at random.
33 If B<seed_len> is less than the length of q, an error is returned.
35 DSA_generate_parameters_ex() places the iteration count in
36 *B<counter_ret> and a counter used for finding a generator in
37 *B<h_ret>, unless these are B<NULL>.
39 A callback function may be used to provide feedback about the progress
40 of the key generation. If B<cb> is not B<NULL>, it will be
41 called as shown below. For information on the BN_GENCB structure and the
42 BN_GENCB_call function discussed below, refer to
43 L<BN_generate_prime(3)>.
49 When a candidate for q is generated, B<BN_GENCB_call(cb, 0, m++)> is called
50 (m is 0 for the first candidate).
54 When a candidate for q has passed a test by trial division,
55 B<BN_GENCB_call(cb, 1, -1)> is called.
56 While a candidate for q is tested by Miller-Rabin primality tests,
57 B<BN_GENCB_call(cb, 1, i)> is called in the outer loop
58 (once for each witness that confirms that the candidate may be prime);
59 i is the loop counter (starting at 0).
63 When a prime q has been found, B<BN_GENCB_call(cb, 2, 0)> and
64 B<BN_GENCB_call(cb, 3, 0)> are called.
68 Before a candidate for p (other than the first) is generated and tested,
69 B<BN_GENCB_call(cb, 0, counter)> is called.
73 When a candidate for p has passed the test by trial division,
74 B<BN_GENCB_call(cb, 1, -1)> is called.
75 While it is tested by the Miller-Rabin primality test,
76 B<BN_GENCB_call(cb, 1, i)> is called in the outer loop
77 (once for each witness that confirms that the candidate may be prime).
78 i is the loop counter (starting at 0).
82 When p has been found, B<BN_GENCB_call(cb, 2, 1)> is called.
86 When the generator has been found, B<BN_GENCB_call(cb, 3, 1)> is called.
90 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
91 instead a newly allocated B<DSA> structure is returned. Additionally "old
92 style" callbacks are used instead of the newer BN_GENCB based approach.
93 Refer to L<BN_generate_prime(3)> for further information.
97 DSA_generate_parameters_ex() returns a 1 on success, or 0 otherwise.
99 DSA_generate_parameters() returns a pointer to the DSA structure, or
100 B<NULL> if the parameter generation fails.
102 The error codes can be obtained by L<ERR_get_error(3)>.
106 Seed lengths E<gt> 20 are not supported.
110 L<dsa(3)>, L<ERR_get_error(3)>, L<rand(3)>,
111 L<DSA_free(3)>, L<BN_generate_prime(3)>