Abstract: In order to solve the secure communication problem, on the basis of studying the chaotic synchronous, this paper designs a hyperchaos secure communication system based on state observer. The hyperchaos Liu system is applied as model of the chaotic system, it can improve the system security efficiently. According to whether the n×n row matrix is full rank, it can judge two hyperchaos systems whether or not achieve synchronism, and avoid the Lyapunov index computation of high dimensional system. 〖JP2〗The method is of widespread applicability. The chaotic system uses the en(t)=y2+(1+x2)p(t) as the cryptographic function, can ensure the flexibility of secure communication. Theoretical analysis and experimental results show that the hyperchaos secure communication system has the characteristics of high security, wide applicability and supporting a certain dynamic adjustment.

Key words: nonlinear, chaotic synchronous, secure communication, hyperchaos Liu system