Audio Encryption Scheme Using Self-Adaptive Bit Scrambling and Two Multi Chaotic-Based Dynamic DNA Computations

In this paper, a novel scheme for secure audio transmission is introduced. The novelty of this scheme is that it combines four different techniques for audio encryption in the same scheme which makes it more secure: self-adaptive scrambling, multi chaotic maps, dynamic DNA encoding and cipher feedback encryption. Also, it introduces two new designed multi chaotic maps as pseudo random generators that combine five different chaotic maps with eight control parameters. The scheme consists of three phases with three secret keys. The first phase is a self-adaptive bit scrambling where SHA512 of the input audio is computed to be used as a first secret key for cyclic shifting the input audio binary stream which efficiently reduces the strong correlation between neighboring audio samples. The second phase is a dynamic DNA encoding of the scrambled audio by using a second secret key obtained from a pseudo random generator (LCS) using a novel design of multi chaotic maps including Sine, Chebyshev and Logistic map with three control parameters. As DNA encoding provides fast computations and large capacity for data transmission, the third phase consists of two DNA algebraic operations “AND” and “XOR” using a pseudorandom DNA sequence as a third secret key generated by another new designed multi chaotic HLG map which combines Henon, Logistic and Gaussian chaotic maps and has five control parameters. The third phase is structured in a cipher feedback mode and so it achieves strong diffusion and confusion in the encrypted audio. Also combining five different chaotic maps in the proposed scheme increases the number of secret control parameters which achieves a huge key space and so robust strength against brute force attacks. The scheme is evaluated by using different measurements including signal to noise ratio (SNR), peak signal to noise ratio (PSNR), number of samples change rate (NSCR), unified average changing intensity (UACI), root mean square (RMS), crest factor (CF), correlation coefficient, histogram, key sensitivity and key space. From results, it is clear that the scheme is highly secure and stronger than many recent similar audio encryption schemes against different types of attacks.