Subscriber unit for generating a stream cipher

Abstract

One embodiment of the invention is a subscriber unit for transmitting communication signals. The subscriber unit comprises a cipher stream generator which generates a cipher stream to encipher a digital data stream. A data stream mixer mixes the cipher stream with the digital data stream. An antenna radiates the mixed cipher and data stream as a communication signal. Another embodiment of the invention is a subscriber unit for receiving communication signals. The subscriber unit comprises a cipher stream generator for generating a cipher stream with the received communication signal to produce a decoded data stream. The cipher steam generator includes first and second linear feedback shift registers. Each has a clock input and an output. The outputs are combined to generate the cipher stream. The output of the second register is combined with a clock signal which is inputted to the clock input to the first register.

Dependencies are inferred from the claim text.