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DSA_generate_parameters
Section: OpenSSL (3)
Updated: 2002-09-25
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NAME
DSA_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
DSA_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:
- *
-
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 witness 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.
RETURN VALUE
DSA_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 ALSO
dsa(3), ERR_get_error(3), rand(3),
DSA_free(3)
HISTORY
DSA_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.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- BUGS
-
- SEE ALSO
-
- HISTORY
-
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