1.\" $OpenBSD: EVP_OpenInit.3,v 1.8 2019/06/07 20:46:25 schwarze Exp $ 2.\" OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100 3.\" 4.\" This file was written by Dr. Stephen Henson <steve@openssl.org>. 5.\" Copyright (c) 2000 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: June 7 2019 $ 52.Dt EVP_OPENINIT 3 53.Os 54.Sh NAME 55.Nm EVP_OpenInit , 56.Nm EVP_OpenUpdate , 57.Nm EVP_OpenFinal 58.Nd EVP envelope decryption 59.Sh SYNOPSIS 60.In openssl/evp.h 61.Ft int 62.Fo EVP_OpenInit 63.Fa "EVP_CIPHER_CTX *ctx" 64.Fa "EVP_CIPHER *type" 65.Fa "unsigned char *ek" 66.Fa "int ekl" 67.Fa "unsigned char *iv" 68.Fa "EVP_PKEY *priv" 69.Fc 70.Ft int 71.Fo EVP_OpenUpdate 72.Fa "EVP_CIPHER_CTX *ctx" 73.Fa "unsigned char *out" 74.Fa "int *outl" 75.Fa "unsigned char *in" 76.Fa "int inl" 77.Fc 78.Ft int 79.Fo EVP_OpenFinal 80.Fa "EVP_CIPHER_CTX *ctx" 81.Fa "unsigned char *out" 82.Fa "int *outl" 83.Fc 84.Sh DESCRIPTION 85The EVP envelope routines are a high level interface to envelope 86decryption. 87They decrypt a public key encrypted symmetric key and then decrypt data 88using it. 89.Pp 90.Fn EVP_OpenInit 91initializes a cipher context 92.Fa ctx 93for decryption with cipher 94.Fa type . 95It decrypts the encrypted symmetric key of length 96.Fa ekl 97bytes passed in the 98.Fa ek 99parameter using the private key 100.Fa priv . 101The IV is supplied in the 102.Fa iv 103parameter. 104.Pp 105.Fn EVP_OpenUpdate 106and 107.Fn EVP_OpenFinal 108have exactly the same properties as the 109.Xr EVP_DecryptUpdate 3 110and 111.Xr EVP_DecryptFinal 3 112routines. 113.Pp 114It is possible to call 115.Fn EVP_OpenInit 116twice in the same way as 117.Xr EVP_DecryptInit 3 . 118The first call should have 119.Fa priv 120set to 121.Dv NULL 122and (after setting any cipher parameters) it should be 123called again with 124.Fa type 125set to 126.Dv NULL . 127.Pp 128If the cipher passed in the 129.Fa type 130parameter is a variable length cipher then the key length will be set to 131the value of the recovered key length. 132If the cipher is a fixed length cipher then the recovered key length 133must match the fixed cipher length. 134.Sh RETURN VALUES 135.Fn EVP_OpenInit 136returns 0 on error or a non-zero integer (actually the recovered secret 137key size) if successful. 138.Pp 139.Fn EVP_OpenUpdate 140returns 1 for success or 0 for failure. 141.Pp 142.Fn EVP_OpenFinal 143returns 0 if the decrypt failed or 1 for success. 144.Sh SEE ALSO 145.Xr evp 3 , 146.Xr EVP_EncryptInit 3 , 147.Xr EVP_SealInit 3 148.Sh HISTORY 149.Fn EVP_OpenInit , 150.Fn EVP_OpenUpdate , 151and 152.Fn EVP_OpenFinal 153first appeared in SSLeay 0.5.1 and have been available since 154.Ox 2.4 . 155