VB6 to PHP convert short function

Hello I need to convert this VB6 function into a php function. When I input "loffkkcgjnaeokqdqgmj" into the function it should output "[login to view URL]:17478". Thanks '//////////////CODE START Public Function LW2IP(sLWKey As String) As String On Error GoTo err Dim key As String Dim Ip As String Dim ippointer As Long Dim keypointer As Long Dim LWKey As String LWKey = sLWKey key = "TYXUYZUVXWSTZSWSZSVRT" ippointer = 12 keypointer = 1 Ip = "" Do Until ippointer = Len(LWKey) - 13 Ip = Ip & Chr$(Asc(Mid$(LWKey, ippointer, 1)) - Asc(Mid$(key, keypointer, 1)) + 32) ippointer = ippointer + 1 keypointer = keypointer + 1 Loop LW2IP = Replace(Ip, " ", vbNullString) Exit Function err: LW2IP = "invalid ip" End Function '/////////////////CODE STOP