Synchronization of random bit generators based on coupled chaotic lasers and application to cryptography.

Random bit generators (RBGs) constitute an important tool in cryptography, stochastic simulations and secure communications. The later in particular has some difficult requirements: high generation rate of unpredictable bit strings and secure key-exchange protocols over public channels. Deterministic algorithms generate pseudo-random number sequences at high rates, however, their unpredictability is limited by the very nature of their deterministic origin.

Zero-lag synchronization and multiple time delays in two coupled chaotic systems.

Zero-lag synchronization (ZLS) between two chaotic systems coupled by a portion of their signal is achieved for restricted ratios between the delays of the self-feedback and the mutual coupling. We extend this scenario to the case of a set of multiple self-feedbacks {Ndi} and a set of multiple mutual couplings {Ncj}. We demonstrate both analytically and numerically that ZLS can be achieved when SigmaliNdi+igmamjNcj=0, where li,mj(epsilon)Z.