EVP_EncryptInit(3) is among the most important "how to drive" manuals,

but it is still excessively long and complicated.  To reduce the amount
of distractions a bit, split out three deprecated functions into a new
manual page EVP_CIPHER_CTX_init(3).  No text change.

In part suggested by tb@, who agrees with the direction.

1 files changed, 150 insertions, 0 deletions

diff --git a/src/lib/libcrypto/man/EVP_CIPHER_CTX_init.3 b/src/lib/libcrypto/man/EVP_CIPHER_CTX_init.3
new file mode 100644
index 0000000000..3bb40018f5
--- /dev/null
+++ b/src/lib/libcrypto/man/EVP_CIPHER_CTX_init.3
@@ -0,0 +1,150 @@
+.\" $OpenBSD: EVP_CIPHER_CTX_init.3,v 1.1 2023/12/01 10:40:21 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 Ingo Schwarze <schwarze@openbsd.org>
+.\"
+.\" 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 Dr. Stephen Henson <steve@openssl.org>
+.\" and Richard Levitte <levitte@openssl.org>.
+.\" Copyright (c) 2000-2001, 2015 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: December 1 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 inl"
+.Fc
+.Sh DESCRIPTION
+.Fn EVP_CIPHER_CTX_init
+is a deprecated function to clear a cipher context on the stack
+before use.
+Do not use it on a cipher context returned from
+.Xr EVP_CIPHER_CTX_new 3
+or one that was already used.
+.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
+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 inl
+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 inl
+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
+and
+.Fn EVP_Cipher
+return 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 .