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<title>DSA_sign</title>
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<ul id="index">
<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 id="NAME">NAME</h1>
<p>DSA_sign, DSA_sign_setup, DSA_verify - DSA signatures</p>
<h1 id="SYNOPSIS">SYNOPSIS</h1>
<pre><code> #include <openssl/dsa.h>
int DSA_sign(int type, const unsigned char *dgst, int len,
unsigned char *sigret, unsigned int *siglen, DSA *dsa);
int DSA_sign_setup(DSA *dsa, BN_CTX *ctx, BIGNUM **kinvp, BIGNUM **rp);
int DSA_verify(int type, const unsigned char *dgst, int len,
unsigned char *sigbuf, int siglen, DSA *dsa);</code></pre>
<h1 id="DESCRIPTION">DESCRIPTION</h1>
<p>DSA_sign() computes a digital signature on the <b>len</b> byte message digest <b>dgst</b> using the private key <b>dsa</b> and places its ASN.1 DER encoding at <b>sigret</b>. The length of the signature is places in *<b>siglen</b>. <b>sigret</b> must point to DSA_size(<b>dsa</b>) bytes of memory.</p>
<p>DSA_sign_setup() 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 DSA_sign_setup() cannot be used anyway: calling this function will only cause overhead, and does not affect the actual signature (pre-)computation.</p>
<p>DSA_verify() verifies that the signature <b>sigbuf</b> of size <b>siglen</b> matches a given message digest <b>dgst</b> of size <b>len</b>. <b>dsa</b> is the signer's public key.</p>
<p>The <b>type</b> parameter is ignored.</p>
<p>The random generator must be seeded when DSA_sign() (or DSA_sign_setup()) is called. If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to external circumstances (see <a href="../man7/RAND.html">RAND(7)</a>), the operation will fail.</p>
<h1 id="RETURN-VALUES">RETURN VALUES</h1>
<p>DSA_sign() and DSA_sign_setup() return 1 on success, 0 on error. DSA_verify() returns 1 for a valid signature, 0 for an incorrect signature and -1 on error. The error codes can be obtained by <a href="../man3/ERR_get_error.html">ERR_get_error(3)</a>.</p>
<h1 id="CONFORMING-TO">CONFORMING TO</h1>
<p>US Federal Information Processing Standard FIPS 186 (Digital Signature Standard, DSS), ANSI X9.30</p>
<h1 id="SEE-ALSO">SEE ALSO</h1>
<p><a href="../man3/DSA_new.html">DSA_new(3)</a>, <a href="../man3/ERR_get_error.html">ERR_get_error(3)</a>, <a href="../man3/RAND_bytes.html">RAND_bytes(3)</a>, <a href="../man3/DSA_do_sign.html">DSA_do_sign(3)</a>, <a href="../man7/RAND.html">RAND(7)</a></p>
<h1 id="COPYRIGHT">COPYRIGHT</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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