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In this paper, we numerically evaluate a hardware-based method for authentication using a pair of twin chaotic lasers. This method belongs to the PUF (Physically Unclonable Function) class; however, it does not require storing the response of the hardware in a database, because both users own the same hardware (one of the twin chaotic lasers), producing, on the fly, the same response, i.e., the same chaotic waveform, when subject to the same stimulus (injection from a third laser) in the same working conditions (local injection, pump current). A bit sequence can be easily obtained from the chaotic waveforms by electronic processing, and authentication consists in comparing the sequences produced by the twin lasers. This scheme is proposed above all for authentication of a client in an unsecure environment to a server in a secure environment, but it can be used also for peer-to-peer authentication. Both the case of open- and close-loop chaotic lasers are considered. Simulations are based on the Lang-Kobayashi model. [ABSTRACT FROM AUTHOR]

In this paper, we numerically evaluate a method that could be tried by an eavesdropper to force the standard two-laser scheme of chaos private transmission. This method is based on the 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. The simulations are based on the Lang–Kobayashi model. [ABSTRACT FROM AUTHOR]

In this paper, we compare the performances of the well-known two-laser and three-laser chaos communications schemes, in terms of privacy. It is found by numerical analysis that in optimized conditions both methods are well suited for private transmission. However, while the three-laser scheme gives its optimum performance with the twin laser pair, the two-laser scheme reaches its best performance using two slightly different lasers (the optimum pair). This results in an easier device selection and in a slightly higher privacy level of the three-laser scheme. Using a twin pair with the two-laser scheme still offers a good level of privacy in most cases; however, in principle the eavesdropper has a chance to extract the message, by selecting a suitable laser. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, we numerically demonstrate private data transmission using twin semiconductor lasers in which chaotic dynamics and synchronization are achieved by optical injection into the laser pair of a common, chaotic driving-signal, generated by a third laser subject to delayed optical feedback. This laser is selected with different parameters with respect to the twin pair, so that the emissions of the synchronized, matched lasers are highly correlated, whereas their correlation with the driver is low. The digital message modulates the emission of the transmitter, as in a standard CM scheme. Message recovery is then obtained by subtracting, from the transmitted chaos-masked message, the chaos, locally generated by the synchronized receiver laser. Simulations have been performed with the Lang-Kobayashi model, keeping into account both laser and photodetector noise. Private transmission has been demonstrated by investigating the effect of the parameter mismatch, between transmitter and receiver, on synchronization and message recovery. [ABSTRACT FROM AUTHOR]

In this paper, we numerically demonstrate secure data transmission, using synchronized "twin" semiconductor lasers working in the chaotic regime, which represent the transmitter and receiver of a cryptographic scheme, compatible with free-space optics technology for line-of-sight communication links. Chaotic dynamics and synchronization are obtained by current injection into the laser pair of a common, chaotic driving-signal. Results of simulations are reported for the configuration in which the chaotic driving-current is obtained by photodetection of the emission of a third laser (driver), chaotic by delayed optical feedback in a short cavity scheme, selected with different parameters with respect to the laser pair. The emissions of the synchronized, matched lasers are highly correlated, whereas their correlation with the driver is low. The digital message modulates the pumping current of the transmitter. Message recovery is performed by subtracting the chaos, locally generated by the synchronized receiver laser, from the signal obtained by photodetection (at the receiver side) of the chaos-masked message transmitted in free space. Simulations have been performed with the Lang- Kobayashi model, keeping into account both attenuation of the optical signal in a line-of-sight configuration, and noise. Security has been investigated and demonstrated by considering the effect, on synchronization and message recovery, of the parameter mismatch between transmitter and receiver. [ABSTRACT FROM AUTHOR]