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<?xml version="1.0" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>BN_rand</title> <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <link rev="made" href="mailto:root@hsxx.drive.ne.jp" /> </head> <body style="background-color: white"> <!-- INDEX BEGIN --> <div name="index"> <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="#notes">NOTES</a></li> <li><a href="#return_values">RETURN VALUES</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> </ul> <hr name="index" /> </div> <!-- INDEX END --> <p> </p> <hr /> <h1><a name="name">NAME</a></h1> <p>BN_rand, BN_priv_rand, BN_pseudo_rand, BN_rand_range, BN_priv_rand_range, BN_pseudo_rand_range - generate pseudo-random number</p> <p> </p> <hr /> <h1><a name="synopsis">SYNOPSIS</a></h1> <pre> #include <openssl/bn.h></pre> <pre> int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);</pre> <pre> int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom);</pre> <pre> int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);</pre> <pre> int BN_rand_range(BIGNUM *rnd, BIGNUM *range);</pre> <pre> int BN_priv_rand_range(BIGNUM *rnd, BIGNUM *range);</pre> <pre> int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range);</pre> <p> </p> <hr /> <h1><a name="description">DESCRIPTION</a></h1> <p><code>BN_rand()</code> generates a cryptographically strong pseudo-random number of <strong>bits</strong> in length and stores it in <strong>rnd</strong>. If <strong>bits</strong> is less than zero, or too small to accommodate the requirements specified by the <strong>top</strong> and <strong>bottom</strong> parameters, an error is returned. The <strong>top</strong> parameters specifies requirements on the most significant bit of the generated number. If it is <strong>BN_RAND_TOP_ANY</strong>, there is no constraint. If it is <strong>BN_RAND_TOP_ONE</strong>, the top bit must be one. If it is <strong>BN_RAND_TOP_TWO</strong>, the two most significant bits of the number will be set to 1, so that the product of two such random numbers will always have 2*<strong>bits</strong> length. If <strong>bottom</strong> is <strong>BN_RAND_BOTTOM_ODD</strong>, the number will be odd; if it is <strong>BN_RAND_BOTTOM_ANY</strong> it can be odd or even. If <strong>bits</strong> is 1 then <strong>top</strong> cannot also be <strong>BN_RAND_TOP_TWO</strong>.</p> <p><code>BN_rand_range()</code> generates a cryptographically strong pseudo-random number <strong>rnd</strong> in the range 0 <= <strong>rnd</strong> < <strong>range</strong>.</p> <p><code>BN_priv_rand()</code> and <code>BN_priv_rand_range()</code> have the same semantics as <code>BN_rand()</code> and <code>BN_rand_range()</code> respectively. They are intended to be used for generating values that should remain private, and mirror the same difference between <em>RAND_bytes(3)</em> and <em>RAND_priv_bytes(3)</em>.</p> <p> </p> <hr /> <h1><a name="notes">NOTES</a></h1> <p>Always check the error return value of these functions and do not take randomness for granted: an error occurs if the CSPRNG has not been seeded with enough randomness to ensure an unpredictable byte sequence.</p> <p> </p> <hr /> <h1><a name="return_values">RETURN VALUES</a></h1> <p>The functions return 1 on success, 0 on error. The error codes can be obtained by <em>ERR_get_error(3)</em>.</p> <p> </p> <hr /> <h1><a name="see_also">SEE ALSO</a></h1> <p><em>ERR_get_error(3)</em>, <em>RAND_add(3)</em>, <em>RAND_bytes(3)</em>, <em>RAND_priv_bytes(3)</em>, <em>RAND(7)</em>, <em>RAND_DRBG(7)</em></p> <p> </p> <hr /> <h1><a name="history">HISTORY</a></h1> <ul> <li> <p>Starting with OpenSSL release 1.1.0, <code>BN_pseudo_rand()</code> has been identical to <code>BN_rand()</code> and <code>BN_pseudo_rand_range()</code> has been identical to <code>BN_rand_range()</code>. The "pseudo" functions should not be used and may be deprecated in a future release.</p> </li> <li> <p>The <code>BN_priv_rand()</code> and <code>BN_priv_rand_range()</code> functions were added in OpenSSL 1.1.1.</p> </li> </ul> <p> </p> <hr /> <h1><a name="copyright">COPYRIGHT</a></h1> <p>Copyright 2000-2021 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> </body> </html>