130 lines
4.4 KiB
HTML
130 lines
4.4 KiB
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<?xml version="1.0" ?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<title>RAND_bytes</title>
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<meta http-equiv="content-type" content="text/html; charset=utf-8" />
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<link rev="made" href="mailto:root@localhost" />
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</head>
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<body style="background-color: white">
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<!-- INDEX BEGIN -->
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<div name="index">
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<p><a name="__index__"></a></p>
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<ul>
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<li><a href="#name">NAME</a></li>
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<li><a href="#synopsis">SYNOPSIS</a></li>
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<li><a href="#description">DESCRIPTION</a></li>
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<li><a href="#notes">NOTES</a></li>
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<li><a href="#return_values">RETURN VALUES</a></li>
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<li><a href="#see_also">SEE ALSO</a></li>
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<li><a href="#history">HISTORY</a></li>
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<li><a href="#copyright">COPYRIGHT</a></li>
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</ul>
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<hr name="index" />
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</div>
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<!-- INDEX END -->
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<p>
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</p>
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<hr />
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<h1><a name="name">NAME</a></h1>
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<p>RAND_bytes, RAND_priv_bytes, RAND_bytes_ex, RAND_priv_bytes_ex,
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RAND_pseudo_bytes - generate random data</p>
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<p>
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</p>
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<hr />
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<h1><a name="synopsis">SYNOPSIS</a></h1>
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<pre>
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#include <openssl/rand.h></pre>
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<pre>
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int RAND_bytes(unsigned char *buf, int num);
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int RAND_priv_bytes(unsigned char *buf, int num);</pre>
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<pre>
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int RAND_bytes_ex(OPENSSL_CTX *ctx, unsigned char *buf, int num);
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int RAND_priv_bytes_ex(OPENSSL_CTX *ctx, unsigned char *buf, int num);</pre>
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<p>Deprecated since OpenSSL 1.1.0, can be hidden entirely by defining
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<strong>OPENSSL_API_COMPAT</strong> with a suitable version value, see
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<em>openssl_user_macros(7)</em>:</p>
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<pre>
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int RAND_pseudo_bytes(unsigned char *buf, int num);</pre>
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<p>
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</p>
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<hr />
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<h1><a name="description">DESCRIPTION</a></h1>
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<p><code>RAND_bytes()</code> puts <strong>num</strong> cryptographically strong pseudo-random bytes
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into <strong>buf</strong>.</p>
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<p><code>RAND_priv_bytes()</code> has the same semantics as <code>RAND_bytes()</code>. It is intended to
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be used for generating values that should remain private. If using the
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default RAND_METHOD, this function uses a separate "private" PRNG
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instance so that a compromise of the "public" PRNG instance will not
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affect the secrecy of these private values, as described in <em>RAND(7)</em>
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and <em>RAND_DRBG(7)</em>.</p>
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<p><code>RAND_bytes_ex()</code> and <code>RAND_priv_bytes_ex()</code> are the same as <code>RAND_bytes()</code> and
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<code>RAND_priv_bytes()</code> except that they both take an additional <em>ctx</em> parameter.
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The DRBG used for the operation is the public or private DRBG associated with
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the specified <em>ctx</em>. The parameter can be NULL, in which case
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the default library context is used (see <em>OPENSSL_CTX(3)</em>.
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If the default RAND_METHOD has been changed then for compatibility reasons the
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RAND_METHOD will be used in preference and the DRBG of the library context
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ignored.</p>
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<p>
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</p>
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<hr />
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<h1><a name="notes">NOTES</a></h1>
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<p>Always check the error return value of <code>RAND_bytes()</code> and
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<code>RAND_priv_bytes()</code> and do not take randomness for granted: an error occurs
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if the CSPRNG has not been seeded with enough randomness to ensure an
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unpredictable byte sequence.</p>
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<p>
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</p>
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<hr />
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<h1><a name="return_values">RETURN VALUES</a></h1>
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<p><code>RAND_bytes()</code> and <code>RAND_priv_bytes()</code>
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return 1 on success, -1 if not supported by the current
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RAND method, or 0 on other failure. The error code can be
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obtained by <em>ERR_get_error(3)</em>.</p>
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<p>
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</p>
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<hr />
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<h1><a name="see_also">SEE ALSO</a></h1>
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<p><em>RAND_add(3)</em>,
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<em>RAND_bytes(3)</em>,
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<em>RAND_priv_bytes(3)</em>,
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<em>ERR_get_error(3)</em>,
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<em>RAND(7)</em>,
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<em>RAND_DRBG(7)</em></p>
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<p>
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</p>
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<hr />
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<h1><a name="history">HISTORY</a></h1>
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<ul>
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<li>
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<p><code>RAND_pseudo_bytes()</code> was deprecated in OpenSSL 1.1.0; use <code>RAND_bytes()</code> instead.</p>
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</li>
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<li>
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<p>The <code>RAND_priv_bytes()</code> function was added in OpenSSL 1.1.1.</p>
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</li>
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<li>
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<p>The <code>RAND_bytes_ex()</code> and <code>RAND_priv_bytes_ex()</code> functions were added in OpenSSL 3.0</p>
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</li>
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</ul>
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<p>
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</p>
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<hr />
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<h1><a name="copyright">COPYRIGHT</a></h1>
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<p>Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.</p>
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<p>Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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<a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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</body>
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</html>
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