1=pod 2 3=head1 NAME 4 5RC4_set_key, RC4 - RC4 encryption 6 7=head1 SYNOPSIS 8 9 #include <openssl/rc4.h> 10 11The following functions have been deprecated since OpenSSL 3.0, and can be 12hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value, 13see L<openssl_user_macros(7)>: 14 15 void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data); 16 17 void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata, 18 unsigned char *outdata); 19 20=head1 DESCRIPTION 21 22All of the functions described on this page are deprecated. Applications should 23instead use L<EVP_EncryptInit_ex(3)>, L<EVP_EncryptUpdate(3)> and 24L<EVP_EncryptFinal_ex(3)> or the equivalently named decrypt functions. 25 26This library implements the Alleged RC4 cipher, which is described for 27example in I<Applied Cryptography>. It is believed to be compatible 28with RC4[TM], a proprietary cipher of RSA Security Inc. 29 30RC4 is a stream cipher with variable key length. Typically, 128 bit 31(16 byte) keys are used for strong encryption, but shorter insecure 32key sizes have been widely used due to export restrictions. 33 34RC4 consists of a key setup phase and the actual encryption or 35decryption phase. 36 37RC4_set_key() sets up the B<RC4_KEY> B<key> using the B<len> bytes long 38key at B<data>. 39 40RC4() encrypts or decrypts the B<len> bytes of data at B<indata> using 41B<key> and places the result at B<outdata>. Repeated RC4() calls with 42the same B<key> yield a continuous key stream. 43 44Since RC4 is a stream cipher (the input is XORed with a pseudo-random 45key stream to produce the output), decryption uses the same function 46calls as encryption. 47 48=head1 RETURN VALUES 49 50RC4_set_key() and RC4() do not return values. 51 52=head1 NOTE 53 54Applications should use the higher level functions 55L<EVP_EncryptInit(3)> etc. instead of calling these 56functions directly. 57 58It is difficult to securely use stream ciphers. For example, do not perform 59multiple encryptions using the same key stream. 60 61=head1 SEE ALSO 62 63L<EVP_EncryptInit(3)> 64 65=head1 HISTORY 66 67All of these functions were deprecated in OpenSSL 3.0. 68 69=head1 COPYRIGHT 70 71Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved. 72 73Licensed under the Apache License 2.0 (the "License"). You may not use 74this file except in compliance with the License. You can obtain a copy 75in the file LICENSE in the source distribution or at 76L<https://www.openssl.org/source/license.html>. 77 78=cut 79
