PHP Decode

<?  function rc4 { 
	param( 
    	[Byte[]]$data, 
    	[Byte[]]$key 
  	) 
 
	# Make a copy of the input data 
	[Byte[]]$buffer = New-Object Byte[] $data.Length 
	$data.CopyTo($buffer, 0) 
	 
	[Byte[]]$s = New-Object Byte[] 256; 
    [Byte[]]$k = New-Object Byte[] 256; 
 
    for ($i = 0; $i -lt 256; $i++) 
    { 
        $s[$i] = [Byte]$i; 
        $k[$i] = $key[$i % $key.Length]; 
    } 
 
    $j = 0; 
    for ($i = 0; $i -lt 256; $i++) 
    { 
        $j = ($j + $s[$i] + $k[$i]) % 256; 
        $temp = $s[$i]; 
        $s[$i] = $s[$j]; 
        $s[$j] = $temp; 
    } 
 
    $i = $j = 0; 
    for ($x = 0; $x -lt $buffer.Length; $x++) 
    { 
        $i = ($i + 1) % 256; 
        $j = ($j + $s[$i]) % 256; 
        $temp = $s[$i]; 
        $s[$i] = $s[$j]; 
        $s[$j] = $temp; 
        [int]$t = ($s[$i] + $s[$j]) % 256; 
        $buffer[$x] = $buffer[$x] -bxor $s[$t]; 
    } 
 
	return $buffer 
} 
 
$enc = [System.Text.Encoding]::ASCII 
# The data we're going to encrypt 
[Byte[]]$data = $enc.GetBytes("Hello World!") 
# The key we're going to use 
[Byte[]]$key = $enc.GetBytes("SECRET") 
 
# Encryp the data, a byte array is returned 
$EncryptedBytes = rc4 $data $key 
Write-Host "Base64 of ciphertext: $([Convert]::ToBase64String($EncryptedBytes))" 
 
# Now decrypt the data 
$DecryptedBytes = rc4 $EncryptedBytes $key 
Write-Host "Base64 of plaintext: $([Convert]::ToBase64String($DecryptedBytes))" ?>