1.\" $OpenBSD: BN_CTX_new.3,v 1.10 2023/04/25 17:21:51 tb Exp $ 2.\" OpenSSL aafbe1cc Jun 12 23:42:08 2013 +0100 3.\" 4.\" This file was written by Ulf Moeller <ulf@openssl.org>. 5.\" Copyright (c) 2000, 2013 The OpenSSL Project. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in 16.\" the documentation and/or other materials provided with the 17.\" distribution. 18.\" 19.\" 3. All advertising materials mentioning features or use of this 20.\" software must display the following acknowledgment: 21.\" "This product includes software developed by the OpenSSL Project 22.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 23.\" 24.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 25.\" endorse or promote products derived from this software without 26.\" prior written permission. For written permission, please contact 27.\" openssl-core@openssl.org. 28.\" 29.\" 5. Products derived from this software may not be called "OpenSSL" 30.\" nor may "OpenSSL" appear in their names without prior written 31.\" permission of the OpenSSL Project. 32.\" 33.\" 6. Redistributions of any form whatsoever must retain the following 34.\" acknowledgment: 35.\" "This product includes software developed by the OpenSSL Project 36.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" 37.\" 38.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 39.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 40.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 41.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 42.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 43.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 44.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 45.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 46.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 47.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 48.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 49.\" OF THE POSSIBILITY OF SUCH DAMAGE. 50.\" 51.Dd $Mdocdate: April 25 2023 $ 52.Dt BN_CTX_NEW 3 53.Os 54.Sh NAME 55.Nm BN_CTX_new , 56.Nm BN_CTX_free 57.Nd allocate and free BN_CTX structures 58.Sh SYNOPSIS 59.In openssl/bn.h 60.Ft BN_CTX * 61.Fo BN_CTX_new 62.Fa void 63.Fc 64.Ft void 65.Fo BN_CTX_free 66.Fa "BN_CTX *c" 67.Fc 68.Sh DESCRIPTION 69A 70.Vt BN_CTX 71is a structure that holds 72.Vt BIGNUM 73temporary variables used by library functions. 74Since dynamic memory allocation to create 75.Vt BIGNUM Ns s 76is rather expensive when used in conjunction with repeated subroutine 77calls, the 78.Vt BN_CTX 79structure is used. 80.Pp 81.Fn BN_CTX_new 82allocates and initializes a 83.Vt BN_CTX 84structure. 85.Pp 86.Fn BN_CTX_free 87frees the components of the 88.Vt BN_CTX 89and, if it was created by 90.Fn BN_CTX_new , 91also the structure itself. 92If 93.Xr BN_CTX_start 3 94has been used on the 95.Vt BN_CTX , 96.Xr BN_CTX_end 3 97must be called before the 98.Vt BN_CTX 99may be freed by 100.Fn BN_CTX_free . 101If 102.Fa c 103is a 104.Dv NULL 105pointer, no action occurs. 106.Sh RETURN VALUES 107.Fn BN_CTX_new 108returns a pointer to the 109.Vt BN_CTX . 110If the allocation fails, it returns 111.Dv NULL 112and sets an error code that can be obtained by 113.Xr ERR_get_error 3 . 114.Sh SEE ALSO 115.Xr BN_add 3 , 116.Xr BN_CTX_start 3 , 117.Xr BN_new 3 118.Sh HISTORY 119.Fn BN_CTX_new 120and 121.Fn BN_CTX_free 122first appeared in SSLeay 0.5.1 and have been available since 123.Ox 2.4 . 124