DSA_generate_parameters(3) OpenSSL 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);
DESCRIPTIONDSA_generate_parameters() generates primes p and q and a
generator g for use in the DSA.
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 random. 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.
DSA_generate_parameters() 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:
o When a candidate for q is generated, callback(0, m++,
cb_arg) is called (m is 0 for the first candidate).
o 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 witness that confirms that the
candidate may be prime); i is the loop counter
(starting at 0).
o When a prime q has been found, callback(2, 0, cb_arg)
and callback(3, 0, cb_arg) are called.
o Before a candidate for p (other than the first) is
generated and tested, callback(0, counter, cb_arg) is
called.
o 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
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DSA_generate_parameters(3) OpenSSL DSA_generate_parameters(3)
candidate may be prime). i is the loop counter
(starting at 0).
o When p has been found, callback(2, 1, cb_arg) is
called.
o When the generator has been found, callback(3, 1,
cb_arg) is called.
RETURN VALUEDSA_generate_parameters() returns a pointer to the DSA
structure, or NULL if the parameter generation fails. The
error codes can be obtained by ERR_get_error(3).
BUGS
Seed lengths > 20 are not supported.
SEE ALSOdsa(3), err(3), rand(3), DSA_free(3)HISTORYDSA_generate_parameters() 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), i.e.
once for each witness. =cut
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