Digital key chaos-communication systems with delay time concealment

We propose a scheme based on a double opto-electronic feedback system which allows on one hand to integrate a digital key required for decoding and on the other to conceal the delay time so that it cannot be identified from the time series using the typical methods. The scheme we propose is based on high speed phase chaos, with constant intensity and an essentially featureless power spectrum, and includes a send delay line in which a key random bit sequence (RBS) is included.