Extracting messages masked by chaotic signals of time-delay systems

We show how to extract messages masked by a chaotic signal of a: time-delay system with very high dimensions and many positive Lyapunov exponents. Usi ng a special embedding coordinate, the infinite-dimensional phase space of the time-delay system is projected onto a special three-dimensional space, which enables us to identify the time delay of the system from-the transmit ted signal and reconstruct the chaotic dynamics to unmask the hidden messag e successfully. The message extraction procedure is illustrated by simulati ons with the Mackey-Glass time-delay system for two types of masking scheme s and different kinds of messages. [S1063-651X(99)06604-0].