1.\" $OpenBSD: EVP_PKEY_CTX_new.3,v 1.16 2024/12/06 14:27:49 schwarze Exp $ 2.\" full merge up to: OpenSSL df75c2bf Dec 9 01:02:36 2018 +0100 3.\" 4.\" This file is a derived work. 5.\" The changes are covered by the following Copyright and license: 6.\" 7.\" Copyright (c) 2019, 2020 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 Dr. Stephen Henson <steve@openssl.org>. 22.\" Copyright (c) 2006, 2009, 2015 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: December 6 2024 $ 69.Dt EVP_PKEY_CTX_NEW 3 70.Os 71.Sh NAME 72.Nm EVP_PKEY_CTX_new , 73.Nm EVP_PKEY_CTX_new_id , 74.Nm EVP_PKEY_CTX_dup , 75.Nm EVP_PKEY_CTX_free 76.Nd public key algorithm context functions 77.Sh SYNOPSIS 78.In openssl/evp.h 79.Ft EVP_PKEY_CTX * 80.Fo EVP_PKEY_CTX_new 81.Fa "EVP_PKEY *pkey" 82.Fa "ENGINE *engine" 83.Fc 84.Ft EVP_PKEY_CTX * 85.Fo EVP_PKEY_CTX_new_id 86.Fa "int id" 87.Fa "ENGINE *engine" 88.Fc 89.Ft EVP_PKEY_CTX * 90.Fo EVP_PKEY_CTX_dup 91.Fa "EVP_PKEY_CTX *ctx" 92.Fc 93.Ft void 94.Fo EVP_PKEY_CTX_free 95.Fa "EVP_PKEY_CTX *ctx" 96.Fc 97.Sh DESCRIPTION 98The 99.Fn EVP_PKEY_CTX_new 100function allocates a public key algorithm context using the algorithm 101specified in 102.Fa pkey . 103The 104.Fa ENGINE *engine 105argument is always ignored and passing 106.Dv NULL 107is recommended. 108.Pp 109The 110.Fn EVP_PKEY_CTX_new_id 111function allocates a public key algorithm context using the algorithm 112specified by 113.Fa id . 114The 115.Fa ENGINE *engine 116argument is always ignored and passing 117.Dv NULL 118is recommended. 119It is normally used when no 120.Vt EVP_PKEY 121structure is associated with the operations, for example during 122parameter generation of key generation for some algorithms. 123The 124.Fa id 125argument can be any of the constants that 126.Xr EVP_PKEY_base_id 3 127and 128.Xr EVP_PKEY_id 3 129may return. 130.Pp 131.Fn EVP_PKEY_CTX_dup 132duplicates the context 133.Fa ctx . 134.Pp 135.Fn EVP_PKEY_CTX_free 136frees up the context 137.Fa ctx . 138If 139.Fa ctx 140is a 141.Dv NULL 142pointer, no action occurs. 143.Sh RETURN VALUES 144.Fn EVP_PKEY_CTX_new , 145.Fn EVP_PKEY_CTX_new_id , 146and 147.Fn EVP_PKEY_CTX_dup 148return either the newly allocated 149.Vt EVP_PKEY_CTX 150structure or 151.Dv NULL 152if an error occurred. 153.Sh SEE ALSO 154.Xr EVP_DigestSignInit 3 , 155.Xr EVP_DigestVerifyInit 3 , 156.Xr EVP_PKEY_base_id 3 , 157.Xr EVP_PKEY_CTX_ctrl 3 , 158.Xr EVP_PKEY_CTX_get_operation 3 , 159.Xr EVP_PKEY_CTX_hkdf_mode 3 , 160.Xr EVP_PKEY_decrypt 3 , 161.Xr EVP_PKEY_derive 3 , 162.Xr EVP_PKEY_encrypt 3 , 163.Xr EVP_PKEY_keygen 3 , 164.Xr EVP_PKEY_new 3 , 165.Xr EVP_PKEY_sign 3 , 166.Xr EVP_PKEY_verify 3 , 167.Xr EVP_PKEY_verify_recover 3 , 168.Xr RSA_pkey_ctx_ctrl 3 , 169.Xr X25519 3 170.Sh HISTORY 171These functions first appeared in OpenSSL 1.0.0 172and have been available since 173.Ox 4.9 . 174.Sh CAVEATS 175The 176.Vt EVP_PKEY_CTX 177structure is an opaque public key algorithm context used by the OpenSSL 178high level public key API. 179Contexts 180.Sy MUST NOT 181be shared between threads. 182It is not permissible to use the same context simultaneously in two 183threads. 184