1DSA_generate_parameters(3)          OpenSSL         DSA_generate_parameters(3)
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NAME

6       DSA_generate_parameters_ex, DSA_generate_parameters - generate DSA
7       parameters
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SYNOPSIS

10        #include <openssl/dsa.h>
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12        int DSA_generate_parameters_ex(DSA *dsa, int bits,
13                       const unsigned char *seed,int seed_len,
14                       int *counter_ret, unsigned long *h_ret, BN_GENCB *cb);
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16       Deprecated:
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18        DSA *DSA_generate_parameters(int bits, unsigned char *seed,
19                       int seed_len, int *counter_ret, unsigned long *h_ret,
20                       void (*callback)(int, int, void *), void *cb_arg);
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DESCRIPTION

23       DSA_generate_parameters_ex() generates primes p and q and a generator g
24       for use in the DSA and stores the result in dsa.
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26       bits is the length of the prime to be generated; the DSS allows a
27       maximum of 1024 bits.
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29       If seed is NULL or seed_len < 20, the primes will be generated at
30       random. Otherwise, the seed is used to generate them. If the given seed
31       does not yield a prime q, a new random seed is chosen.
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33       DSA_generate_parameters_ex() places the iteration count in *counter_ret
34       and a counter used for finding a generator in *h_ret, unless these are
35       NULL.
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37       A callback function may be used to provide feedback about the progress
38       of the key generation. If cb is not NULL, it will be called as shown
39       below. For information on the BN_GENCB structure and the BN_GENCB_call
40       function discussed below, refer to BN_generate_prime(3).
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42       ·   When a candidate for q is generated, BN_GENCB_call(cb, 0, m++) is
43           called (m is 0 for the first candidate).
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45       ·   When a candidate for q has passed a test by trial division,
46           BN_GENCB_call(cb, 1, -1) is called.  While a candidate for q is
47           tested by Miller-Rabin primality tests, BN_GENCB_call(cb, 1, i) is
48           called in the outer loop (once for each witness that confirms that
49           the candidate may be prime); i is the loop counter (starting at 0).
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51       ·   When a prime q has been found, BN_GENCB_call(cb, 2, 0) and
52           BN_GENCB_call(cb, 3, 0) are called.
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54       ·   Before a candidate for p (other than the first) is generated and
55           tested, BN_GENCB_call(cb, 0, counter) is called.
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57       ·   When a candidate for p has passed the test by trial division,
58           BN_GENCB_call(cb, 1, -1) is called.  While it is tested by the
59           Miller-Rabin primality test, BN_GENCB_call(cb, 1, i) is called in
60           the outer loop (once for each witness that confirms that the
61           candidate may be prime).  i is the loop counter (starting at 0).
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63       ·   When p has been found, BN_GENCB_call(cb, 2, 1) is called.
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65       ·   When the generator has been found, BN_GENCB_call(cb, 3, 1) is
66           called.
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68       DSA_generate_parameters() (deprecated) works in much the same way as
69       for DSA_generate_parameters_ex, except that no dsa parameter is passed
70       and instead a newly allocated DSA structure is returned. Additionally
71       "old style" callbacks are used instead of the newer BN_GENCB based
72       approach.  Refer to BN_generate_prime(3) for further information.
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RETURN VALUE

75       DSA_generate_parameters_ex() returns a 1 on success, or 0 otherwise.
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77       DSA_generate_parameters() returns a pointer to the DSA structure, or
78       NULL if the parameter generation fails.
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80       The error codes can be obtained by ERR_get_error(3).
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BUGS

83       Seed lengths > 20 are not supported.
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SEE ALSO

86       dsa(3), ERR_get_error(3), rand(3), DSA_free(3), BN_generate_prime(3)
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HISTORY

89       DSA_generate_parameters() appeared in SSLeay 0.8. The cb_arg argument
90       was added in SSLeay 0.9.0.  In versions up to OpenSSL 0.9.4,
91       callback(1, ...) was called in the inner loop of the Miller-Rabin test
92       whenever it reached the squaring step (the parameters to callback did
93       not reveal how many witnesses had been tested); since OpenSSL 0.9.5,
94       callback(1, ...)  is called as in BN_is_prime(3), i.e. once for each
95       witness.
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991.0.2o                            2018-03-27        DSA_generate_parameters(3)