Encryption in the physical layer based on spectral encoding implanted by DSP and applied to optical networks

Abstract

The objective of this project is to evaluate the application of a new technique of signal encryption to optical communication systems. The technique consists of using digital signal processing to: i) divide an input signal into several spectral slices, ii) apply a phase shift and delay own to each slice, and iii) spectrally multiplex all slices, iv) to generate an electronic output signal which is an encrypted (distorted) version of the input signal. The cryptographic key corresponds to the set of phases and delays used in this process. The encrypted electronic signal can then be modulated in an optical carrier and propagated by a transparent optical network. Agents that monitor some of the network unauthorizedly will not be able to recover the content of the signal due to the encryption used. At the authorized destination node, where the cryptographic key is known, the optical signal is converted to the electronic domain and processed digitally to decipher the signal. This is done by applying phase shifts and delays that are complementary to those used in encryption. To the best of our knowledge, this technique has never been addressed in the literature and, depending on its performance, has potential for commercial application. In this project, the technique will be implemented by codes written in Matlab and its performance will be evaluated through simulations in the software VPITransmissionMaker. A partnership with the CPqD Foundation will allow the realization of physical experiments to evaluate this technique. The proposal is part of our group's work with the Fotonicom 2 Program of the National Institutes of Science and Technology promoted by CNPq.