| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | RC4_set_key, RC4 - RC4 encryption
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| 6 |
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| 7 | =head1 SYNOPSIS
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| 8 |
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| 9 | #include <openssl/rc4.h>
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| 10 |
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| 11 | void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data);
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| 12 |
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| 13 | void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
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| 14 | unsigned char *outdata);
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| 15 |
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| 16 | =head1 DESCRIPTION
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| 17 |
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| 18 | This library implements the Alleged RC4 cipher, which is described for
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| 19 | example in I<Applied Cryptography>. It is believed to be compatible
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| 20 | with RC4[TM], a proprietary cipher of RSA Security Inc.
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| 21 |
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| 22 | RC4 is a stream cipher with variable key length. Typically, 128 bit
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| 23 | (16 byte) keys are used for strong encryption, but shorter insecure
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| 24 | key sizes have been widely used due to export restrictions.
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| 25 |
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| 26 | RC4 consists of a key setup phase and the actual encryption or
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| 27 | decryption phase.
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| 28 |
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| 29 | RC4_set_key() sets up the B<RC4_KEY> B<key> using the B<len> bytes long
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| 30 | key at B<data>.
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| 31 |
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| 32 | RC4() encrypts or decrypts the B<len> bytes of data at B<indata> using
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| 33 | B<key> and places the result at B<outdata>. Repeated RC4() calls with
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| 34 | the same B<key> yield a continuous key stream.
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| 35 |
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| 36 | Since RC4 is a stream cipher (the input is XORed with a pseudo-random
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| 37 | key stream to produce the output), decryption uses the same function
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| 38 | calls as encryption.
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| 39 |
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| 40 | =head1 RETURN VALUES
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| 41 |
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| 42 | RC4_set_key() and RC4() do not return values.
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| 43 |
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| 44 | =head1 NOTE
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| 45 |
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| 46 | Applications should use the higher level functions
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| 47 | L<EVP_EncryptInit(3)> etc. instead of calling these
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| 48 | functions directly.
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| 49 |
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| 50 | It is difficult to securely use stream ciphers. For example, do not perform
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| 51 | multiple encryptions using the same key stream.
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| 52 |
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| 53 | =head1 SEE ALSO
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| 54 |
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| 55 | L<EVP_EncryptInit(3)>
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| 56 |
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| 57 | =head1 COPYRIGHT
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| 58 |
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| 59 | Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
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| 60 |
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| 61 | Licensed under the OpenSSL license (the "License"). You may not use
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| 62 | this file except in compliance with the License. You can obtain a copy
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| 63 | in the file LICENSE in the source distribution or at
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| 64 | L<https://www.openssl.org/source/license.html>.
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| 65 |
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| 66 | =cut
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