Private Communications Using Optical Chaos

After a brief summary of the basic methods for secure transmission using optical chaos, we report on most recent achievements, namely, on the comparison between the standard two-laser and the three-laser schemes and on the network architecture for multiuser secure transmission. From our investigations, we found that while both the basic two-laser and the three-laser schemes are suitable to secure data exchange, the three-laser scheme offers a better level of privacy due to its symmetrical topology. Moreover, while transmission based on optical chaos is usually restricted to point-to-point interconnections, a more advanced solution, derived from the well-known public key cryptography, allows for private message transmission between any couple of subscribers in a network

Assessing security of chaos communications against eavesdropping by pump detection

In this paper, we numerically evaluate a method which could be tried by an eavesdropper to force the standard two-laser scheme of chaos private transmission. This method is based on detection of the voltage arising across a semiconductor laser junction, and uses two lasers: one is synchronized to the transmitter (thus, reproducing chaos and rejecting the message), the other is selected and trimmed to copy the transmitter (i.e., reproducing both chaos and the message). The message is then obtained by difference and chaos cancellation. By assuming the usual parameter mismatch, which is expected to be achieved by an eavesdropper, it is shown that the method does not represent a substantial threat to the privacy of the transmission system. The scheme is also briefly considered as an alternative, but less performant, scheme for chaotic cryptography. Simulations are based on the Lang-Kobayashi model

Enhancing Privacy of Chaotic Communications by Double Masking

In this paper, we numerically demonstrate that the performances of private transmission using chaotic lasers can be substantially improved by double masking the message by a suitable scheme. In addition to standard optical chaos, our method makes use of the chaotic voltage waveform available across the transmitter laser junction.With respect to the standard setup, the new one requires only one more electrical amplifier and a passive adder at the transmitter, while the receiver remains unchanged. It has been found that with this new scheme, synchronization quality is significantly improved for the twin lasers, while this is not the case for an unmatched laser pair. This results in an increased bit error rate differential between the authorized user and an eavesdropper, thus enhancing privacy. Simulations have been performed with the Lang–Kobayashi model