Speech Scrambler Based on Discrete Cosine Transform and Novel Seven-Dimension Hyper Chaotic System

Abstract

Because of their inherent features related to cryptography, the hyperchaotic system has strong potential in security systems. In this paper, a new cryptography scheme for speech scrambling has been proposed which gives it more security level. Also, it introduced a novel seven dimensions (7D) nonlinear hyperchaotic system in third-order which has twelve positive parameters. A chaotic behavior for the proposed novel system is analyzed. The hyperchaotic system is demonstrated that beside it appropriates for speech scrambler. PRNG (Pseudo Random Number Generated) is created based on the proposed 7D hyperchaotic result. The proposed scheme depends on this novel hyperchaotic system as PRNG to generate a random keystream bit. The input speech signal in this work is first squeezed by discrete cosine transformation (DCT) to minimize the residual intelligibility (R. I.). Increasing the number of system parameters accomplished a high key space, therefore, improves the security to resist several cryptographic attacks. The scheme is measured using various tests like. Peak Signal-to-Noise Ratio (PSNR), Signal to noise ratio (SNR), percentage of Difference (P. Diff.), Segmental Signal to Noise Ratio Measure (SSNR), Crest factor measure (CF), Correlation coefficient Measure (R_C), root mean square measure (RMS), histogram, key sensitivity, spectrogram, and waveform The results of simulation and comparison prove that the algorithm can achieve better performance in encryption that means the scheme is stronger and highly secure against various types of attacks than many recent similar audio encryption schemes. Simulated and implemented the result using Mathematica and MATLAB programs to simulation results, provided qualitatively, and figures.