.\" $OpenBSD: EVP_CIPHER_CTX_init.3,v 1.3 2023/12/26 22:13:00 schwarze Exp $ .\" full merge up to: .\" OpenSSL EVP_EncryptInit.pod 0874d7f2 Oct 11 13:13:47 2022 +0100 .\" .\" This file is a derived work. .\" The changes are covered by the following Copyright and license: .\" .\" Copyright (c) 2018, 2019, 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. 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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: December 26 2023 $ .Dt EVP_CIPHER_CTX_INIT 3 .Os .Sh NAME .Nm EVP_CIPHER_CTX_init , .Nm EVP_CIPHER_CTX_cleanup , .Nm EVP_Cipher .Nd obsolete EVP cipher functions .Sh SYNOPSIS .In openssl/evp.h .Ft void .Fo EVP_CIPHER_CTX_init .Fa "EVP_CIPHER_CTX *ctx" .Fc .Ft int .Fo EVP_CIPHER_CTX_cleanup .Fa "EVP_CIPHER_CTX *ctx" .Fc .Ft int .Fo EVP_Cipher .Fa "EVP_CIPHER_CTX *ctx" .Fa "unsigned char *out" .Fa "const unsigned char *in" .Fa "unsigned int in_len" .Fc .Sh DESCRIPTION .Fn EVP_CIPHER_CTX_init is a deprecated function that could be used to clear a cipher context on the stack before .Vt EVP_CIPHER_CTX was made opaque. Calling it on a cipher context just returned from .Xr EVP_CIPHER_CTX_new 3 has no effect. Calling it on a cipher context that was already used leaks memory. Instead, use .Xr EVP_CIPHER_CTX_reset 3 or .Xr EVP_CIPHER_CTX_free 3 . .Pp .Fn EVP_CIPHER_CTX_cleanup is a deprecated alias for .Xr EVP_CIPHER_CTX_reset 3 . It clears all information from .Fa ctx and frees all allocated memory associated with it, except the .Fa ctx object itself. .Pp .Fn EVP_Cipher exposes implementation details of the functions .Xr EVP_CipherUpdate 3 and .Xr EVP_CipherFinal 3 that should never have become part of the public API. .Pp If the flag .Dv EVP_CIPH_FLAG_CUSTOM_CIPHER is set for the cipher used by .Fa ctx , behaviour depends on .Fa in . If that argument is .Dv NULL and .Fa in_len is 0, behaviour is similar to .Xr EVP_CipherFinal 3 ; if .Fa in_len is not 0, behaviour is undefined. If .Fa in is not .Dv NULL , behaviour is similar to .Xr EVP_CipherUpdate 3 . In both cases, the exceptions to the similarity are that arguments and return values differ. .Pp If the flag .Dv EVP_CIPH_FLAG_CUSTOM_CIPHER is not set for the cipher used by .Fa ctx , it encrypts or decrypts aligned blocks of data whose lengths match the cipher block size. It requires that the previous encryption or decryption operation using the same .Fa ctx , if there was any, ended exactly on a block boundary and that .Fa in_len is an integer multiple of the cipher block size. If either of these conditions is violated, .Fn EVP_Cipher silently produces incorrect results. For that reason, using the function .Xr EVP_CipherUpdate 3 instead is strongly recommended. The latter can safely handle partial blocks, and even if .Fa in_len actually is a multiple of the cipher block size for all calls, the overhead incurred by using .Xr EVP_CipherUpdate 3 is minimal. .Sh RETURN VALUES .Fn EVP_CIPHER_CTX_cleanup returns 1 for success or 0 for failure. .Pp With .Dv EVP_CIPH_FLAG_CUSTOM_CIPHER , .Fn EVP_Cipher returns the number of bytes written to .Fa out for success or \-1 for failure. Without .Dv EVP_CIPH_FLAG_CUSTOM_CIPHER , it returns 1 for success or 0 for failure. .Sh SEE ALSO .Xr evp 3 , .Xr EVP_EncryptInit 3 .Sh HISTORY .Fn EVP_Cipher first appeared in SSLeay 0.6.5. .Fn EVP_CIPHER_CTX_cleanup first appeared in SSLeay 0.8.0. .Fn EVP_CIPHER_CTX_init first appeared in SSLeay 0.9.0. All these functions have been available since .Ox 2.4 . .Sh CAVEATS Checking the return value of .Fn EVP_Cipher requires unusual caution: zero signals success if .Dv EVP_CIPH_FLAG_CUSTOM_CIPHER is set or failure otherwise.