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.\" $OpenBSD: RC4.3,v 1.8 2020/03/29 17:05:02 schwarze Exp $
.\" OpenSSL 99d63d46 Oct 26 13:56:48 2016 -0400
.\"
.\" This file was written by Ulf Moeller <ulf@openssl.org>.
.\" Copyright (c) 2000 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: March 29 2020 $
.Dt RC4 3
.Os
.Sh NAME
.Nm RC4_set_key ,
.Nm RC4
.Nd RC4 encryption
.Sh SYNOPSIS
.In openssl/rc4.h
.Ft void
.Fo RC4_set_key
.Fa "RC4_KEY *key"
.Fa "int len"
.Fa "const unsigned char *data"
.Fc
.Ft void
.Fo RC4
.Fa "RC4_KEY *key"
.Fa "unsigned long len"
.Fa "const unsigned char *indata"
.Fa "unsigned char *outdata"
.Fc
.Sh DESCRIPTION
This library implements the alleged RC4 cipher, which is described for
example in
.Qq Applied Cryptography .
It is believed to be compatible with RC4[TM], a proprietary cipher of
RSA Security Inc.
.Pp
RC4 is a stream cipher with variable key length.
Typically, 128-bit (16-byte) keys are used for strong encryption, but
shorter insecure key sizes have been widely used due to export
restrictions.
.Pp
RC4 consists of a key setup phase and the actual encryption or
decryption phase.
.Pp
.Fn RC4_set_key
sets up the
.Vt RC4_KEY
.Fa key
using the
.Fa len
bytes long key at
.Fa data .
.Pp
.Fn RC4
encrypts or decrypts the
.Fa len
bytes of data at
.Fa indata
using
.Fa key
and places the result at
.Fa outdata .
Repeated
.Fn RC4
calls with the same
.Fa key
yield a continuous key stream.
.Pp
Since RC4 is a stream cipher (the input is XOR'ed with a pseudo-random
key stream to produce the output), decryption uses the same function
calls as encryption.
.Sh SEE ALSO
.Xr blowfish 3 ,
.Xr EVP_EncryptInit 3 ,
.Xr EVP_rc4 3
.Sh HISTORY
.Fn RC4_set_key
and
.Fn RC4
appeared in SSLeay 0.4 or earlier and have been available since
.Ox 2.4 .
.Sh BUGS
This cipher is broken and should no longer be used.
|
