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DSA_generate_parameters(3) - DSA_generate_parameters - generate DSA parameters - man 3 DSA_generate_parameters

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DSA_generate_parameters(3)          OpenSSL         DSA_generate_parameters(3)



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(1,8) the DSA.

       bits is the length of the prime to be generated; the DSS allows a maxi-
       mum 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(3,4,6) seed is chosen and placed at
       seed.

       DSA_generate_parameters() places the iteration count in(1,8) *counter_ret
       and a counter used for finding a generator in(1,8) *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, call-
           back(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(1,8) 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 call-
           back(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, call-
           back(1, -1, cb_arg) is called.  While it is tested by the Miller-
           Rabin primality test, callback(1, i, cb_arg) is called in(1,8) 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(3,n) the parameter generation fails. The error(8,n) codes can be obtained
       by ERR_get_error(3).

BUGS
       Seed lengths > 20 are not supported.

SEE ALSO
       dsa(1,3)(3), ERR_get_error(3), rand(1,3)(3), DSA_free(3)

HISTORY
       DSA_generate_parameters() appeared in(1,8) SSLeay 0.8. The cb_arg argument
       was added in(1,8) SSLeay 0.9.0.  In versions up to OpenSSL 0.9.4, call-
       back(1, ...) was called in(1,8) 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(1,8) BN_is_prime(3), i.e. once for each
       witness.  =cut



0.9.7d                            2002-09-25        DSA_generate_parameters(3)

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