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<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="#conforming_to">CONFORMING TO</a></li>
<li><a href="#see_also">SEE ALSO</a></li>
<li><a href="#copyright">COPYRIGHT</a></li>
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<h1><a name="name">NAME</a></h1>
<p>DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures</p>
<p>
</p>
<hr />
<h1><a name="synopsis">SYNOPSIS</a></h1>
<pre>
#include <openssl/dsa.h></pre>
<pre>
int DSA_sign(int type, const unsigned char *dgst, int len,
unsigned char *sigret, unsigned int *siglen, DSA *dsa);</pre>
<pre>
int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp, BIGNUM **rp);</pre>
<pre>
int DSA_verify(int type, const unsigned char *dgst, int len,
unsigned char *sigbuf, int siglen, DSA *dsa);</pre>
<p>
</p>
<hr />
<h1><a name="description">DESCRIPTION</a></h1>
<p><code>DSA_sign()</code> computes a digital signature on the <strong>len</strong> byte message
digest <strong>dgst</strong> using the private key <strong>dsa</strong> and places its ASN.1 DER
encoding at <strong>sigret</strong>. The length of the signature is places in
*<strong>siglen</strong>. <strong>sigret</strong> must point to DSA_size(<strong>dsa</strong>) bytes of memory.</p>
<p><code>DSA_sign_setup()</code> is defined only for backward binary compatibility and
should not be used.
Since OpenSSL 1.1.0 the DSA type is opaque and the output of
<code>DSA_sign_setup()</code> cannot be used anyway: calling this function will only
cause overhead, and does not affect the actual signature
(pre-)computation.</p>
<p><code>DSA_verify()</code> verifies that the signature <strong>sigbuf</strong> of size <strong>siglen</strong>
matches a given message digest <strong>dgst</strong> of size <strong>len</strong>.
<strong>dsa</strong> is the signer's public key.</p>
<p>The <strong>type</strong> parameter is ignored.</p>
<p>The random generator must be seeded when <code>DSA_sign()</code> (or DSA_sign_setup())
is called.
If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to
external circumstances (see <em>RAND(7)</em>), the operation will fail.</p>
<p>
</p>
<hr />
<h1><a name="return_values">RETURN VALUES</a></h1>
<p><code>DSA_sign()</code> and <code>DSA_sign_setup()</code> return 1 on success, 0 on error.
<code>DSA_verify()</code> returns 1 for a valid signature, 0 for an incorrect
signature and -1 on error. The error codes can be obtained by
<em>ERR_get_error(3)</em>.</p>
<p>
</p>
<hr />
<h1><a name="conforming_to">CONFORMING TO</a></h1>
<p>US Federal Information Processing Standard FIPS 186 (Digital Signature
Standard, DSS), ANSI X9.30</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_do_sign(3)</em>,
<em>RAND(7)</em></p>
<p>
</p>
<hr />
<h1><a name="copyright">COPYRIGHT</a></h1>
<p>Copyright 2000-2019 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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