Abstract: A novel four-dimensional hyperchaotic system was constructed, and its basic characteristics of the nonli-near dynamics system were analyzed in detail. Active control synchronization method was used to design appropriate nonli near feedback controller, and this synchronization system was applied in chaotic secret communication, which implemented synchronization between the four-dimensional hyperchaotic system and thre}dimensional Lorenz system with different dimensions and different structures. Numerical simulation results show that this scheme is feasible and applicable.

Key words: Hyperchaotic system, Chaotic synchronization, Active control method, Secret communication