The basic ideas of the signal encryption algorithms can be classified into three major types: position permutation, value transformation and the combination form. In this paper, a new signal security system and its VLSI architecture are proposed. The encryption algorithm belongs to the combination form. Based on two bit-circulation functions with parameters controlled by a chaotic binary sequence, every eight pixels are value-transformed and then position-permuted in each bit plane. The scheme is analyzed and shown to have high security. In order to implement the system, its VLSI architecture with low hardware cost, high computing speeds, high modularity, regularity, and locality is designed.