Three-loop electro-optical phase chaotic secure communication system with time-delay signatures concealment and key space enhancement

Abstract

A novel three loops electro-optical phase (TLEOP) chaotic secure communication system is proposed, which consists of three mutually coupled electro-optical phase chaotic feedback loops. A pseudo-random binary sequence (PRBS) is introduced in the proposed system scheme. The scheme improves the complexity of the chaotic carriers and completely the time-delay signatures (TDSs) of the system with a small feedback gain coefficient that is easy to reach. The PRBS or the original messages and the chaotic carriers are nonlinearly coupled together and participate in the generation of the chaotic carrier which further improves the complexity and the security of the chaotic system. Multiple TDSs effectively enlarge the key space of the system (about 1012). The synchronization performance of the proposed TLEOP system is discussed. The results show that the TDSs are suitable as the secret key of the system because of the high sensitivity of the chaos synchronization to time-delays. Since the mismatch of the feedback gain coefficient caused by environmental changes has little effect on the chaos synchronization, the proposed system has strong robustness. The proposed scheme has great application prospects in chaotic secure communication.