An RNS Architecture for Quasi-Chaotic Oscillators

Wideband chaotic carrier is a promising solution for wideband communication, since it overcomes the disadvantages of both narrowband and spread-spectrum communication. It is particularly suited to realize information encryption for secure communication. Chaotic signals can be generated by using discrete-time non-linear dynamical circuits, since they can exhibit a quasi-chaotic (QC) behavior. A particular implementation of QC digital filters can be based on finite precision arithmetic and, in particular, on residue number system (RNS) circuits, which possess very attractive features with regard to their VLSI implementation. In the present paper, we propose an RNS architecture that can be used in connection with secure communication. Each RNS channel consists of a QC oscillator, having its coefficients belonging to a Galois field defined by a prime modulus. In particular, the QC behavior is ensured by well-known properties of primitive polynomials in this field, which generate the characteristic feedback of the oscillator. We demonstrate in the paper that the proposed RNS architecture yields a cost-effective VLSI implementation, which favorably compares with respect to other secure communication approaches proposed in the technical literature. We obtain encouraging results both in terms of confidentiality of the encrypted information and of throughput rate for real-time applications. Moreover, we propose an extended architecture suited to the protection of the secure communication system against transmission errors, by using the self-correcting ability of Redundant RNS (RRNS).