Digital key for chaos communication performing time delay concealment

We introduce a scheme that integrates a digital key in a phase-chaos electro-optical delay system
for optical chaos communications. A pseudo-random binary sequence (PRBS)
is mixed within the chaotic dynamics in a way that a mutual concealment is performed,
e.g. the time delay is hidden by the binary sequence, and the
PRBS is also masked by the chaos. Besides bridging the gap between algorithmic symmetric key
cryptography and chaos-based analog encoding, the proposed approach is intended to benefit from
the complex algebra mixing between a (pseudo-random) boolean variable,
and another continuous time (chaotic) variable. The scheme also provides a large flexibility allowing
for easy reconfigurations to communicate securely at high bit rate between different systems.