A Novel Orbit Perturbation Method for Continuous-Time Chaos to Obtain Dynamic Seeds-Key Stream Cipher

It is possible for continuous-time chaos based stream ciphers to have larger seeds-key space and longer seeds-key than discrete-time chaos based ones. However, they are not applicable because of the many long-length run-courses and very large departure time. The orbit perturbation method to chaotic stranger attractor is proposed to solve the problems. It is proved that the systems keep chaotic after their parameters are overlaid by some chaotic variables. As a result, the run-course closes to the ideal values, and the departure time is decreased greatly. It is verified by Lorenz, Rossler and Chen systems. Using the orbit perturbation method, the chaotic stream ciphers with dynamic seeds-key could be obtained. It is obviously safer than the ones using original chaotic sequences.