Speech Encryption Based on Four-Dimensional Hyperchaotic System

This paper presents speech encryption based on four-dimensional hyperchaotic systems. Higher order chaotic systems can generate pseudo random numbers (PRN) of more complex dynamical properties. Hyper chaotic sequence is proofed with good randomness and unpredictability. In this approach, the speech scrambles are compressed by DCT to reduce residual intelligibility. Coefficients are then masked by PRN to eliminate true sense of original speech signals. Various analysis such as key space, correlation, signal to noise ratio (SNR), and autocorrelation have been also carried out. The results give good correlation and SNR, which validates that the proposed scheme is efficient compared to conventional lower dimensional chaotic cryptosystems. Since the algorithm is simple and fourdimensional, the proposed method is computationally less complex and highly secure against brute-force attack.