Secure communication using Duffing oscillators

In this paper, a Duffing oscillator is used to construct a chaos-based secure communication system for transmitting digital signals. The synchronization of both the transmitter and the receiver is carried out using a Lyapunov-based control approach that observes the states of the transmitter. The parameters of the transmitter are assumed unknown, and are estimated at the receiver side to accomplish two tasks. The first one is to complete the synchronization process, while the second one is to implement a cryptography approach to secure the transmitted message. Different difficulty levels of constructing both the state observer and/or the parameters update laws are investigated, while highlighting the coupling effects between them. Tuning the proposed system, along with meeting hardware constraints when transmitting real-time signals are addressed, and recommendations for improving the performance are discussed.