121 lines
3.9 KiB
HTML
121 lines
3.9 KiB
HTML
<?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>EVP_RAND-JITTER</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>
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<ul id="index">
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<li><a href="#NAME">NAME</a></li>
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<li><a href="#DESCRIPTION">DESCRIPTION</a>
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<ul>
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<li><a href="#Identity">Identity</a></li>
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<li><a href="#Supported-parameters">Supported parameters</a></li>
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</ul>
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</li>
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<li><a href="#NOTES">NOTES</a></li>
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<li><a href="#EXAMPLES">EXAMPLES</a></li>
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<li><a href="#SEE-ALSO">SEE ALSO</a></li>
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<li><a href="#COPYRIGHT">COPYRIGHT</a></li>
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</ul>
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<h1 id="NAME">NAME</h1>
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<p>EVP_RAND-JITTER - The randomness seed source EVP_RAND implementation</p>
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<h1 id="DESCRIPTION">DESCRIPTION</h1>
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<p>Support for deterministic random number generator seeding through the <b>EVP_RAND</b> API.</p>
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<p>This software seed source produces randomness based on tiny CPU "jitter" fluctuations.</p>
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<p>It is available when OpenSSL is compiled with <b>enable-jitter</b> option. When available it is listed in <b>openssl list -random-generators</b> and <b>openssl info -seeds</b>.</p>
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<h2 id="Identity">Identity</h2>
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<p>"JITTER" is the name for this implementation; it can be used with the EVP_RAND_fetch() function.</p>
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<h2 id="Supported-parameters">Supported parameters</h2>
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<p>The supported parameters are:</p>
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<dl>
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<dt id="state-OSSL_RAND_PARAM_STATE-integer">"state" (<b>OSSL_RAND_PARAM_STATE</b>) <integer></dt>
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<dd>
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</dd>
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<dt id="strength-OSSL_RAND_PARAM_STRENGTH-unsigned-integer">"strength" (<b>OSSL_RAND_PARAM_STRENGTH</b>) <unsigned integer></dt>
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<dd>
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</dd>
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<dt id="max_request-OSSL_RAND_PARAM_MAX_REQUEST-unsigned-integer">"max_request" (<b>OSSL_RAND_PARAM_MAX_REQUEST</b>) <unsigned integer></dt>
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<dd>
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<p>These parameters work as described in <a href="../man3/EVP_RAND.html">"PARAMETERS" in EVP_RAND(3)</a>.</p>
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</dd>
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</dl>
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<h1 id="NOTES">NOTES</h1>
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<p>A context for the seed source can be obtained by calling:</p>
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<pre><code> EVP_RAND *rand = EVP_RAND_fetch(NULL, "JITTER", NULL);
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EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand, NULL);</code></pre>
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<p>The <b>enable-jitter</b> configuration option was added in OpenSSL 3.4.</p>
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<h1 id="EXAMPLES">EXAMPLES</h1>
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<pre><code> EVP_RAND *rand;
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EVP_RAND_CTX *seed, *rctx;
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unsigned char bytes[100];
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OSSL_PARAM params[2], *p = params;
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unsigned int strength = 128;
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/* Create and instantiate a seed source */
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rand = EVP_RAND_fetch(NULL, "JITTER", NULL);
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seed = EVP_RAND_CTX_new(rand, NULL);
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EVP_RAND_instantiate(seed, strength, 0, NULL, 0, NULL);
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EVP_RAND_free(rand);
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/* Feed this into a DRBG */
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rand = EVP_RAND_fetch(NULL, "CTR-DRBG", NULL);
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rctx = EVP_RAND_CTX_new(rand, seed);
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EVP_RAND_free(rand);
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/* Configure the DRBG */
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_CIPHER,
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SN_aes_256_ctr, 0);
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*p = OSSL_PARAM_construct_end();
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EVP_RAND_instantiate(rctx, strength, 0, NULL, 0, params);
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EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);
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EVP_RAND_CTX_free(rctx);
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EVP_RAND_CTX_free(seed);</code></pre>
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<h1 id="SEE-ALSO">SEE ALSO</h1>
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<p><a href="../man3/EVP_RAND.html">EVP_RAND(3)</a>, <a href="../man3/EVP_RAND.html">"PARAMETERS" in EVP_RAND(3)</a></p>
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<h1 id="COPYRIGHT">COPYRIGHT</h1>
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<p>Copyright 2024 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 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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</body>
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</html>
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