Intro
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RC4 (or also known as ARCFOUR) is a symmetric key stream cipher designed by
the RSA in 1987 by Ron Rivest. RC is an acronym for Ron's Code. The 4 is
equal to his 4th algorithm.

With symmetric key encryption the same key is used for encrypting and
decrypting the message.

RC4 is part of some commonly used encryption protocols and standards,
including WEP and WPA for wireless cards and SSL.

More information about RC4 can be obtained from the RSA website.
http://www.rsasecurity.com/rsalabs/node.asp?id=2250

Usage
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The use of the RC4 class is very simple. First you create an instance of the
RC4 class.

[CODE]
$instance = new Crypt_Rc4;
[/CODE]