DSA_generate_parameters(3)DSA_generate_parameters(3)NAMEDSA_generate_parameters - Generate DSA parameters
SYNOPSIS
#include <openssl/dsa.h>
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
);
DESCRIPTION
The DSA_generate_parameters() function generates primes p and q and a
generator g for use in the DSA.
The value of bits is the length of the prime to be generated; the DSS
allows a maximum of 1024 bits.
If seed is NULL or seed_len < 20, the primes will be generated at ran‐
dom. Otherwise, the seed is used to generate them. If the given seed
does not yield a prime q, a new random seed is chosen and placed at
seed.
The DSA_generate_parameters() function places the iteration count in
*counter_ret and a counter used for finding a generator in *h_ret,
unless these are NULL.
A callback function may be used to provide feedback about the progress
of the key generation. If callback is not NULL, it will be called as
follows: When a candidate for q is generated, callback(0, m++, cb_arg)
is called (m is 0 for the first candidate). When a candidate for q has
passed a test by trial division, callback(1, -1, cb_arg) is called.
While a candidate for q is tested by Miller-Rabin primality tests,
callback(1, i, cb_arg) is called in the outer loop (once for each wit‐
ness that confirms that the candidate may be prime); i is the loop
counter (starting at 0). When a prime q has been found, callback(2, 0,
cb_arg) and callback(3, 0, cb_arg) are called. Before a candidate for
p (other than the first) is generated and tested, callback(0, counter,
cb_arg) is called. When a candidate for p has passed the test by trial
division, callback(1, -1, cb_arg) is called. While it is tested by the
Miller-Rabin primality test, callback(1, i, cb_arg) 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). When p has been
found, callback(2, 1, cb_arg) is called. When the generator has been
found, callback(3, 1, cb_arg) is called.
RESTRICTIONS
Seed lengths > 20 are not supported.
RETURN VALUE
The DSA_generate_parameters() function returns a pointer to the DSA
structure, or NULL if the parameter generation fails. The error codes
can be obtained from ERR_get_error().
HISTORY
The DSA_generate_parameters() function appeared in SSLeay 0.8. The
cb_arg argument was added in SSLeay 0.9.0. In versions up to OpenSSL
0.9.4, callback(1, ...) was called in the inner loop of the Miller-
Rabin test whenever it reached the squaring step (the parameters to
callback did not reveal how many witnesses had been tested); since
OpenSSL 0.9.5, callback(1, ...) is called as in BN_is_prime(3), mean‐
ing once for each witness.
SEE ALSO
Functions: dsa(3), err(3), rand(3), DSA_free(3)DSA_generate_parameters(3)
