NAME

       RC4_set_key, RC4 - RC4 encryption

SYNOPSIS

        #include <openssl/rc4.h>

       The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely
       by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

        void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data);

        void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
                 unsigned char *outdata);

DESCRIPTION

       All of the functions described on this page are deprecated. Applications should instead
       use EVP_EncryptInit_ex(3), EVP_EncryptUpdate(3) and EVP_EncryptFinal_ex(3) or the
       equivalently named decrypt functions.

       This library implements the Alleged RC4 cipher, which is described for example in Applied
       Cryptography.  It is believed to be compatible with RC4[TM], a proprietary cipher of RSA
       Security Inc.

       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.

       RC4 consists of a key setup phase and the actual encryption or decryption phase.

       RC4_set_key() sets up the RC4_KEY key using the len bytes long key at data.

       RC4() encrypts or decrypts the len bytes of data at indata using key and places the result
       at outdata.  Repeated RC4() calls with the same key yield a continuous key stream.

       Since RC4 is a stream cipher (the input is XORed with a pseudo-random key stream to
       produce the output), decryption uses the same function calls as encryption.

RETURN VALUES

       RC4_set_key() and RC4() do not return values.

NOTE

       Applications should use the higher level functions EVP_EncryptInit(3) etc. instead of
       calling these functions directly.

       It is difficult to securely use stream ciphers. For example, do not perform multiple
       encryptions using the same key stream.

SEE ALSO

       EVP_EncryptInit(3)

HISTORY

       All of these functions were deprecated in OpenSSL 3.0.

COPYRIGHT

       Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file except
       in compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.