.\" $OpenBSD: EVP_CIPHER_CTX_get_cipher_data.3,v 1.3 2023/08/26 15:12:04 schwarze Exp $ .\" full merge up to: OpenSSL 99d63d46 Oct 26 13:56:48 2016 -0400 .\" .\" This file is a derived work. .\" The changes are covered by the following Copyright and license: .\" .\" Copyright (c) 2023 Ingo Schwarze .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" .\" The original file was written by Matt Caswell . .\" Copyright (c) 2016 The OpenSSL Project. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in .\" the documentation and/or other materials provided with the .\" distribution. .\" .\" 3. All advertising materials mentioning features or use of this .\" software must display the following acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" .\" .\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to .\" endorse or promote products derived from this software without .\" prior written permission. For written permission, please contact .\" openssl-core@openssl.org. .\" .\" 5. Products derived from this software may not be called "OpenSSL" .\" nor may "OpenSSL" appear in their names without prior written .\" permission of the OpenSSL Project. .\" .\" 6. Redistributions of any form whatsoever must retain the following .\" acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" .\" .\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY .\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: August 26 2023 $ .Dt EVP_CIPHER_CTX_GET_CIPHER_DATA 3 .Os .Sh NAME .Nm EVP_CIPHER_CTX_get_cipher_data , .Nm EVP_CIPHER_CTX_set_cipher_data , .Nm EVP_CIPHER_CTX_buf_noconst .Nd inspect and modify EVP_CIPHER_CTX objects .Sh SYNOPSIS .In openssl/evp.h .Ft void * .Fo EVP_CIPHER_CTX_get_cipher_data .Fa "const EVP_CIPHER_CTX *ctx" .Fc .Ft void * .Fo EVP_CIPHER_CTX_set_cipher_data .Fa "EVP_CIPHER_CTX *ctx" .Fa "void *cipher_data" .Fc .Ft unsigned char * .Fo EVP_CIPHER_CTX_buf_noconst .Fa "EVP_CIPHER_CTX *ctx" .Fc .Sh DESCRIPTION .Fn EVP_CIPHER_CTX_get_cipher_data returns a pointer to the cipher data of .Fa ctx . The format and content of this data is specific to the algorithm and to the particular implementation of the cipher. For example, this data can be used by engines to store engine specific information. The data is automatically allocated and freed by OpenSSL, so applications and engines should not normally free this directly (but see below). .Pp .Fn EVP_CIPHER_CTX_set_cipher_data allows an application or engine to replace the existing cipher data with new data, transferring ownership of .Fa cipher_data to the .Fa ctx object. A pointer to any existing cipher data is returned from this function. If the old data is no longer required, it should be freed through a call to .Xr free 3 . .Pp .Fn EVP_CIPHER_CTX_buf_noconst provides engines and custom cipher implementations with access to the internal buffer that .Xr EVP_EncryptUpdate 3 copies input data into before encrypting it. This function can for example be used inside callback functions installed with .Xr EVP_CIPHER_meth_set_do_cipher 3 . .Sh RETURN VALUES .Fn EVP_CIPHER_CTX_get_cipher_data returns an internal pointer owned by .Fa ctx . .Pp .Fn EVP_CIPHER_CTX_set_cipher_data returns a pointer to the old cipher data of .Fa ctx and transfers ownership to the caller. .Pp .Fn EVP_CIPHER_CTX_buf_noconst returns a pointer to an internal buffer owned by .Fa ctx . .Sh SEE ALSO .Xr evp 3 , .Xr EVP_CIPHER_meth_new 3 , .Xr EVP_EncryptInit 3 .Sh HISTORY .Fn EVP_CIPHER_CTX_get_cipher_data , .Fn EVP_CIPHER_CTX_set_cipher_data , and .Fn EVP_CIPHER_CTX_buf_noconst first appeared in OpenSSL 1.1.0 and have been available since .Ox 7.1 .