Edit File: BN_CTX_start.html
<?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_CTX_start</title> <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <link rev="made" href="mailto:root@localhost" /> </head> <body> <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="#SEE-ALSO">SEE ALSO</a></li> <li><a href="#COPYRIGHT">COPYRIGHT</a></li> </ul> <h1 id="NAME">NAME</h1> <p>BN_CTX_start, BN_CTX_get, BN_CTX_end - use temporary BIGNUM variables</p> <h1 id="SYNOPSIS">SYNOPSIS</h1> <pre><code> #include <openssl/bn.h> void BN_CTX_start(BN_CTX *ctx); BIGNUM *BN_CTX_get(BN_CTX *ctx); void BN_CTX_end(BN_CTX *ctx);</code></pre> <h1 id="DESCRIPTION">DESCRIPTION</h1> <p>These functions are used to obtain temporary <b>BIGNUM</b> variables from a <b>BN_CTX</b> (which can been created by using <a href="../man3/BN_CTX_new.html">BN_CTX_new(3)</a>) in order to save the overhead of repeatedly creating and freeing <b>BIGNUM</b>s in functions that are called from inside a loop.</p> <p>A function must call BN_CTX_start() first. Then, BN_CTX_get() may be called repeatedly to obtain temporary <b>BIGNUM</b>s. All BN_CTX_get() calls must be made before calling any other functions that use the <b>ctx</b> as an argument.</p> <p>Finally, BN_CTX_end() must be called before returning from the function. If <b>ctx</b> is NULL, nothing is done. When BN_CTX_end() is called, the <b>BIGNUM</b> pointers obtained from BN_CTX_get() become invalid.</p> <h1 id="RETURN-VALUES">RETURN VALUES</h1> <p>BN_CTX_start() and BN_CTX_end() return no values.</p> <p>BN_CTX_get() returns a pointer to the <b>BIGNUM</b>, or <b>NULL</b> on error. Once BN_CTX_get() has failed, the subsequent calls will return <b>NULL</b> as well, so it is sufficient to check the return value of the last BN_CTX_get() call. In case of an error, an error code is set, which can be obtained by <a href="../man3/ERR_get_error.html">ERR_get_error(3)</a>.</p> <h1 id="SEE-ALSO">SEE ALSO</h1> <p><a href="../man3/BN_CTX_new.html">BN_CTX_new(3)</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> </body> </html>