DSA_generate_parameters_ex, DSA_generate_parameters - generate DSA parameters
int DSA_generate_parameters_ex(DSA *dsa, int bits,
const unsigned char *seed,int seed_len,
int *counter_ret, unsigned long *h_ret, BN_GENCB *cb);
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);
generates primes p and q and a generator g
for use in the DSA and stores the result in dsa
is the length of the prime to be generated; the DSS allows a maximum
of 1024 bits.
< 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.
places the iteration count in *
and a counter used for finding a generator in *
, unless these are NULL
A callback function may be used to provide feedback about the progress of the
key generation. If cb
is not NULL
, it will be called as shown
below. For information on the BN_GENCB structure and the BN_GENCB_call
function discussed below, refer to BN_generate_prime(3)
- When a candidate for q is generated, BN_GENCB_call(cb, 0, m++) is
called (m is 0 for the first candidate).
- When a candidate for q has passed a test by trial division,
BN_GENCB_call(cb, 1, -1) is called. While a candidate for q is
tested by Miller-Rabin primality tests, BN_GENCB_call(cb, 1, i) 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, BN_GENCB_call(cb, 2, 0) and
BN_GENCB_call(cb, 3, 0) are called.
- Before a candidate for p (other than the first) is generated and tested,
BN_GENCB_call(cb, 0, counter) is called.
- When a candidate for p has passed the test by trial division,
BN_GENCB_call(cb, 1, -1) is called. While it is tested by the
Miller-Rabin primality test, BN_GENCB_call(cb, 1, i) 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, BN_GENCB_call(cb, 2, 1) is called.
- When the generator has been found, BN_GENCB_call(cb, 3, 1) is
(deprecated) works in much the same way as for
DSA_generate_parameters_ex, except that no dsa
parameter is passed and
instead a newly allocated DSA
structure is returned. Additionally
"old style" callbacks are used instead of the newer BN_GENCB based
approach. Refer to BN_generate_prime(3)
for further information.
returns a 1 on success, or 0 otherwise.
returns a pointer to the DSA structure, or
if the parameter generation fails.
The error codes can be obtained by ERR_get_error(3)
Seed lengths > 20 are not supported.
appeared in SSLeay 0.8. The cb_arg
argument was added in SSLeay 0.9.0. In versions up to OpenSSL 0.9.4,
was called in the inner loop of the Miller-Rabin test
whenever it reached the squaring step (the parameters to callback
not reveal how many witnesses had been tested); since OpenSSL 0.9.5,
is called as in BN_is_prime(3)
, i.e. once for