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<p><a name="__index__"></a></p>
<ul>
<li><a href="#name">NAME</a></li>
<li><a href="#synopsis">SYNOPSIS</a></li>
<li><a href="#description">DESCRIPTION</a></li>
<li><a href="#return_values">RETURN VALUES</a></li>
<li><a href="#bugs">BUGS</a></li>
<li><a href="#see_also">SEE ALSO</a></li>
<li><a href="#history">HISTORY</a></li>
<li><a href="#copyright">COPYRIGHT</a></li>
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<p>
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<h1><a name="name">NAME</a></h1>
<p>DSA_generate_parameters_ex, DSA_generate_parameters - generate DSA parameters</p>
<p>
</p>
<hr />
<h1><a name="synopsis">SYNOPSIS</a></h1>
<pre>
#include <openssl/dsa.h></pre>
<pre>
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);</pre>
<p>Deprecated:</p>
<pre>
#if OPENSSL_API_COMPAT < 0x00908000L
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);
#endif</pre>
<p>
</p>
<hr />
<h1><a name="description">DESCRIPTION</a></h1>
<p><code>DSA_generate_parameters_ex()</code> generates primes p and q and a generator g
for use in the DSA and stores the result in <strong>dsa</strong>.</p>
<p><strong>bits</strong> is the length of the prime p to be generated.
For lengths under 2048 bits, the length of q is 160 bits; for lengths
greater than or equal to 2048 bits, the length of q is set to 256 bits.</p>
<p>If <strong>seed</strong> is NULL, the primes will be generated at random.
If <strong>seed_len</strong> is less than the length of q, an error is returned.</p>
<p><code>DSA_generate_parameters_ex()</code> places the iteration count in
*<strong>counter_ret</strong> and a counter used for finding a generator in
*<strong>h_ret</strong>, unless these are <strong>NULL</strong>.</p>
<p>A callback function may be used to provide feedback about the progress
of the key generation. If <strong>cb</strong> is not <strong>NULL</strong>, it will be
called as shown below. For information on the BN_GENCB structure and the
BN_GENCB_call function discussed below, refer to
<em>BN_generate_prime(3)</em>.</p>
<p><code>DSA_generate_prime()</code> is similar to <code>DSA_generate_prime_ex()</code> but
expects an old-style callback function; see
<em>BN_generate_prime(3)</em> for information on the old-style callback.</p>
<ul>
<li>
<p>When a candidate for q is generated, <strong>BN_GENCB_call(cb, 0, m++)</strong> is called
(m is 0 for the first candidate).</p>
</li>
<li>
<p>When a candidate for q has passed a test by trial division,
<strong>BN_GENCB_call(cb, 1, -1)</strong> is called.
While a candidate for q is tested by Miller-Rabin primality tests,
<strong>BN_GENCB_call(cb, 1, i)</strong> 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).</p>
</li>
<li>
<p>When a prime q has been found, <strong>BN_GENCB_call(cb, 2, 0)</strong> and
<strong>BN_GENCB_call(cb, 3, 0)</strong> are called.</p>
</li>
<li>
<p>Before a candidate for p (other than the first) is generated and tested,
<strong>BN_GENCB_call(cb, 0, counter)</strong> is called.</p>
</li>
<li>
<p>When a candidate for p has passed the test by trial division,
<strong>BN_GENCB_call(cb, 1, -1)</strong> is called.
While it is tested by the Miller-Rabin primality test,
<strong>BN_GENCB_call(cb, 1, i)</strong> 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).</p>
</li>
<li>
<p>When p has been found, <strong>BN_GENCB_call(cb, 2, 1)</strong> is called.</p>
</li>
<li>
<p>When the generator has been found, <strong>BN_GENCB_call(cb, 3, 1)</strong> is called.</p>
</li>
</ul>
<p>
</p>
<hr />
<h1><a name="return_values">RETURN VALUES</a></h1>
<p><code>DSA_generate_parameters_ex()</code> returns a 1 on success, or 0 otherwise.
The error codes can be obtained by <em>ERR_get_error(3)</em>.</p>
<p><code>DSA_generate_parameters()</code> returns a pointer to the DSA structure or
<strong>NULL</strong> if the parameter generation fails.</p>
<p>
</p>
<hr />
<h1><a name="bugs">BUGS</a></h1>
<p>Seed lengths greater than 20 are not supported.</p>
<p>
</p>
<hr />
<h1><a name="see_also">SEE ALSO</a></h1>
<p><em>DSA_new(3)</em>, <em>ERR_get_error(3)</em>, <em>RAND_bytes(3)</em>,
<em>DSA_free(3)</em>, <em>BN_generate_prime(3)</em></p>
<p>
</p>
<hr />
<h1><a name="history">HISTORY</a></h1>
<p><code>DSA_generate_parameters()</code> was deprecated in OpenSSL 0.9.8; use
<code>DSA_generate_parameters_ex()</code> instead.</p>
<p>
</p>
<hr />
<h1><a name="copyright">COPYRIGHT</a></h1>
<p>Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.</p>
<p>Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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