1.\" $OpenBSD: EVP_CIPHER_CTX_get_cipher_data.3,v 1.3 2023/08/26 15:12:04 schwarze Exp $ 2.\" full merge up to: OpenSSL 99d63d46 Oct 26 13:56:48 2016 -0400 3.\" 4.\" This file is a derived work. 5.\" The changes are covered by the following Copyright and license: 6.\" 7.\" Copyright (c) 2023 Ingo Schwarze <schwarze@openbsd.org> 8.\" 9.\" Permission to use, copy, modify, and distribute this software for any 10.\" purpose with or without fee is hereby granted, provided that the above 11.\" copyright notice and this permission notice appear in all copies. 12.\" 13.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 14.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 15.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 16.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 17.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 18.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 19.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 20.\" 21.\" The original file was written by Matt Caswell <matt@openssl.org>. 22.\" Copyright (c) 2016 The OpenSSL Project. All rights reserved. 23.\" 24.\" Redistribution and use in source and binary forms, with or without 25.\" modification, are permitted provided that the following conditions 26.\" are met: 27.\" 28.\" 1. Redistributions of source code must retain the above copyright 29.\" notice, this list of conditions and the following disclaimer. 30.\" 31.\" 2. Redistributions in binary form must reproduce the above copyright 32.\" notice, this list of conditions and the following disclaimer in 33.\" the documentation and/or other materials provided with the 34.\" distribution. 35.\" 36.\" 3. All advertising materials mentioning features or use of this 37.\" software must display the following acknowledgment: 38.\" "This product includes software developed by the OpenSSL Project 39.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 40.\" 41.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 42.\" endorse or promote products derived from this software without 43.\" prior written permission. For written permission, please contact 44.\" openssl-core@openssl.org. 45.\" 46.\" 5. Products derived from this software may not be called "OpenSSL" 47.\" nor may "OpenSSL" appear in their names without prior written 48.\" permission of the OpenSSL Project. 49.\" 50.\" 6. Redistributions of any form whatsoever must retain the following 51.\" acknowledgment: 52.\" "This product includes software developed by the OpenSSL Project 53.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" 54.\" 55.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 56.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 57.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 58.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 59.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 60.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 61.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 62.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 63.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 64.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 65.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 66.\" OF THE POSSIBILITY OF SUCH DAMAGE. 67.\" 68.Dd $Mdocdate: August 26 2023 $ 69.Dt EVP_CIPHER_CTX_GET_CIPHER_DATA 3 70.Os 71.Sh NAME 72.Nm EVP_CIPHER_CTX_get_cipher_data , 73.Nm EVP_CIPHER_CTX_set_cipher_data , 74.Nm EVP_CIPHER_CTX_buf_noconst 75.Nd inspect and modify EVP_CIPHER_CTX objects 76.Sh SYNOPSIS 77.In openssl/evp.h 78.Ft void * 79.Fo EVP_CIPHER_CTX_get_cipher_data 80.Fa "const EVP_CIPHER_CTX *ctx" 81.Fc 82.Ft void * 83.Fo EVP_CIPHER_CTX_set_cipher_data 84.Fa "EVP_CIPHER_CTX *ctx" 85.Fa "void *cipher_data" 86.Fc 87.Ft unsigned char * 88.Fo EVP_CIPHER_CTX_buf_noconst 89.Fa "EVP_CIPHER_CTX *ctx" 90.Fc 91.Sh DESCRIPTION 92.Fn EVP_CIPHER_CTX_get_cipher_data 93returns a pointer to the cipher data of 94.Fa ctx . 95The format and content of this data is specific to the algorithm 96and to the particular implementation of the cipher. 97For example, this data can be used by engines 98to store engine specific information. 99The data is automatically allocated and freed by OpenSSL, so 100applications and engines should not normally free this directly (but see 101below). 102.Pp 103.Fn EVP_CIPHER_CTX_set_cipher_data 104allows an application or engine to replace the existing cipher data 105with new data, transferring ownership of 106.Fa cipher_data 107to the 108.Fa ctx 109object. 110A pointer to any existing cipher data is returned from this function. 111If the old data is no longer required, 112it should be freed through a call to 113.Xr free 3 . 114.Pp 115.Fn EVP_CIPHER_CTX_buf_noconst 116provides engines and custom cipher implementations 117with access to the internal buffer that 118.Xr EVP_EncryptUpdate 3 119copies input data into before encrypting it. 120This function can for example be used 121inside callback functions installed with 122.Xr EVP_CIPHER_meth_set_do_cipher 3 . 123.Sh RETURN VALUES 124.Fn EVP_CIPHER_CTX_get_cipher_data 125returns an internal pointer owned by 126.Fa ctx . 127.Pp 128.Fn EVP_CIPHER_CTX_set_cipher_data 129returns a pointer to the old cipher data of 130.Fa ctx 131and transfers ownership to the caller. 132.Pp 133.Fn EVP_CIPHER_CTX_buf_noconst 134returns a pointer to an internal buffer owned by 135.Fa ctx . 136.Sh SEE ALSO 137.Xr evp 3 , 138.Xr EVP_CIPHER_meth_new 3 , 139.Xr EVP_EncryptInit 3 140.Sh HISTORY 141.Fn EVP_CIPHER_CTX_get_cipher_data , 142.Fn EVP_CIPHER_CTX_set_cipher_data , 143and 144.Fn EVP_CIPHER_CTX_buf_noconst 145first appeared in OpenSSL 1.1.0 and have been available since 146.Ox 7.1 . 147