Abstract: In an encryption system, a serial data stream is demultiplexed into a plurality N of encryptor input data streams to form a sequence of encryptor input data slices applied to an encryptor having a cascade of stages. Each stage includes a mapping function and a delay function, the mapping function performing a stage-specific direct mapping of data slice values to corresponding generally different data slice values, and the delay function applying stage-specific and generally different delays to individual symbols of data slices. Encrypted data slices generated by the last stage of the encryptor are transmitted through a transmission channel and received at a decryptor having a cascade of stages. Each decryptor stage includes an equalizing delay function and an inverse mapping function to generate output data slices from input data slices.

Abstract: A novel method and apparatus encodes a data signal (e.g., before wireless transmission) such that the encoded signal has Gaussian statistics and the transmitted signal exhibits virtually no signal structure. This approach represents a significant improvement over previous attempts, as no synchronization between the encoder and decoder is required and the linearity of the transfer channel is preserved. Implementations of systems, methods, and apparatus according to embodiments of the invention are disclosed wherein the encoded signal has a flat power spectrum, wherein different codes are assigned to different users, wherein compensation for phase shifts is performed, and wherein the design and/or construction of the implementation may be accomplished using various digital filtering architectures.