hmac md5 - need some tips

[Kyan]

How do I write this in autoit?

function md5_hmac($data, $key)
{
    if (strlen($key) > 64)
        $key = pack('H*', md5($key));
    $key  = str_pad($key, 64, chr(0x00));

    $k_ipad = $key ^ str_repeat(chr(0x36), 64);
    $k_opad = $key ^ str_repeat(chr(0x5c), 64);

    return md5($k_opad . pack('H*', md5($k_ipad . $data)));
}

the pack can be done like this

Func _packH($sInput)
    Local $sReply = ""
    For $xx = 1 To StringLen($sInput) Step 2
        $sReply &= Chr(Dec(StringMid($sInput, $xx, 2)))
    Next
    Return $sReply
EndFunc   ;==>_packH by Luigi

str_pad (don't know if I made some mistake)

Func str_pad($input, $PadLenght, $padChr = Chr(0x00))
    If Not IsNumber($PadLenght) Then SetError(1)
    If StringLen($input) < $PadLenght Then
        Local $out=$input, $c = $PadLenght - StringLen($input)
        For $qwer = 1 To $c
            $out &=$padChr
        Next
    EndIf
    Return $out
EndFunc

str_repeat

Func str_repeat($input, $multi)
    If Not IsNumber($multi) Then SetError(1)
    Local $out = ''
    For $x = 1 To $multi
        $out &= $input
    Next
    Return $out
EndFunc

chr 0x36 = 6 ?
chr 0x56 = \ ?

how can you exp a chr?? WTF