mrc4crypt.class

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<?php
 
// Adapted from Javascript code at http://shop-js.sourceforge.net
// Created On: June 20, 2003
 
class MRC4Crypt
{
    function rc4($key, $text)
    {
        $s = array
            (
            );
 
        for ($i = 0; $i < 256; $i++)
        {
            $s[$i] = $i;
        }
 
        $key_length = strlen($key);
        $y = 0;
 
        for ($x = 0; $x < 256; $x++)
        {
            $c = ord(substr($key, ($x % $key_length), 1));
            $y = ($c + $s[$x] + $y) % 256;
            $temp_swap = $s[$x];
            $s[$x] = $s[$y];
            $s[$y] = $temp_swap;
        }
 
        $cipher = "";
        $x = 0;
        $y = 0;
        $z = "";
 
        for ($x = 0; $x < strlen($text); $x++)
        {
            $x2 = $x % 256;
            $y = ($s[$x2] + $y) % 256;
            $temp = $s[$x2];
            $s[$x2] = $s[$y];
            $s[$y] = $temp;
            $z = $s[(($s[$x2] + $s[$y]) % 256)];
            $cipherby = ord(substr($text, $x, 1)) ^ $z;
            $cipher .= chr($cipherby);
        }
 
        return $cipher;
    }
}
?>