RC4 Decodeing Using PHP - php

Question

I am trying to decode the rc4 encoded value using follwong function.
function rc4($key, $data){
// Store the vectors "S" has calculated
static $SC;
// Function to swaps values of the vector "S"
$swap = create_function('&$v1, &$v2', '
$v1 = $v1 ^ $v2;
$v2 = $v1 ^ $v2;
$v1 = $v1 ^ $v2;
');
$ikey = crc32($key);
if (!isset($SC[$ikey])) {
// Make the vector "S", basead in the key
$S = range(0, 255);
$j = 0;
$n = strlen($key);
for ($i = 0; $i < 255; $i++) {
$char = ord($key{$i % $n});
$j = ($j + $S[$i] + $char) % 256;
$swap($S[$i], $S[$j]);
}
$SC[$ikey] = $S;
} else {
$S = $SC[$ikey];
}
// Crypt/decrypt the data
$n = strlen($data);
$data = str_split($data, 1);
$i = $j = 0;
for ($m = 0; $m < $n; $m++) {
$i = ($i + 1) % 256;
$j = ($j + $S[$i]) % 256;
$swap($S[$i], $S[$j]);
$char = ord($data[$m]);
$char = $S[($S[$i] + $S[$j]) % 256] ^ $char;
$data[$m] = chr($char);
}
return $data; implode('', $data);
}
If i use this function to decode simple text it works fine, but when i go for bigger key, it gives something like this
Œù©>Ç ¾¾óÅ,ŒŒ£f®ãápXŽ×{
Which i am not getting what it is???
Can you please explain whats wrong with it?
My Key is f033b52440607260e131d4f4a0f55cae and data is: 4522261326835a46d78099e0