spoofing clipper serial number secrecy in clipper chip the serial number of the clipper chip is encrypted with the system key and transmitted as one part of a three part message presumably the protocol can be recovered if by nothing else differential analysis postulate if you will a chip or logic sitting between the clipper chip and its communications channel the purpose of this chip is twofold transmit channel the spoof chip xors the bit encrypted serial number with a secondary keying variable this renders the serial number unrecoverable with just the system key recieve channel the spoof chip xors the incoming encrypted serial number with a secondary keying variable assuming the serial number is necessary for local operation this has the net result of hiding the serial number this gets more interesting when the number of serial numbers issued becomes large making it difficult to distinguish between valid serial numbers and a spoofed serial number without knowing the system key you could lie about the serial number but risk detection of the lie if you had the system key and the encryption algorithm you could successfully lie with a lower probability of detection by emulating the format of your own serial number makes you wonder whats being hidden here seems like the secrecy is to prevent you from lying about who you are
