.\" $OpenBSD: EVP_rc4.3,v 1.1 2019/03/21 13:37:25 schwarze Exp $
.\" full merge up to: OpenSSL 8fa4d95e Oct 21 11:59:09 2017 +0900
.\"
.\" This file was written by Ronald Tse <ronald.tse@ribose.com>
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.Dd $Mdocdate: March 21 2019 $
.Dt EVP_RC4 3
.Os
.Sh NAME
.Nm EVP_rc4 ,
.Nm EVP_rc4_40 ,
.Nm EVP_rc4_hmac_md5
.Nd EVP RC4 stream cipher
.Sh SYNOPSIS
.In openssl/evp.h
.Ft const EVP_CIPHER *
.Fn EVP_rc4 void
.Ft const EVP_CIPHER *
.Fn EVP_rc4_40 void
.Ft const EVP_CIPHER *
.Fn EVP_rc4_hmac_md5 void
.Sh DESCRIPTION
These functions provide the RC4 stream cipher in the
.Xr evp 3
framework.
It is a variable key length cipher.
.Pp
.Fn EVP_rc4
uses a default key length of 128 bits.
.Pp
.Fn EVP_rc4_40
uses a key length of 40 bits instead.
This function is deprecated.
Use
.Fn EVP_rc4
and
.Xr EVP_CIPHER_CTX_set_key_length 3
instead.
.Pp
.Fn EVP_rc4_hmac_md5
provides authenticated encryption with the RC4 stream cipher
with MD5 as HMAC.
This function is not intended for usage outside of TLS
and requires calling of some undocumented control functions.
It does not conform to the EVP AEAD interface.
.Sh RETURN VALUES
These functions return an
.Vt EVP_CIPHER
structure that provides the implementation of the symmetric cipher.
.Sh SEE ALSO
.Xr evp 3 ,
.Xr EVP_EncryptInit 3
.Sh HISTORY
.Fn EVP_rc4
first appeared in SSLeay 0.5.1
and
.Fn EVP_rc4_40
in OpenSSL 0.9.1.
These functions have been available since
.Ox 2.4 .
.Pp
.Fn EVP_rc4_hmac_md5
first appeared in OpenSSL 1.0.1 and has been available since
.Ox 5.3 .