Secure speech coding communication using hyperchaotic key generators for AMR-WB codec

Classical cryptosystems are not suitable for all situations for they fail to meet some current security requirements due to their small keyspace, which makes them prone to brute-force attacks, as well as their inefficiency in real-time applications due to their considerable time complexity. Recently, secure applications such as hyperchaos-based speech signals became a focal topic for research. Their properties such as unpredictability and randomness make them an efficient alternative for data protection. In this paper, a new 4D hyperchaotic cryptosystem based on the Lorenz system is introduced by adding a new state to its classical equation for full and partial encryption of speech coded using AMR-WB G.722.2 Codec. For higher computational security, we perform the encryption by combining both confusion and diffusion mechanisms, and to evaluate the efficiency of our proposed cryptosystem scheme, several experiments are carried out on the basis of the waveform and spectrogram analysis, sensitivity analysis, keyspace analysis, statistical analysis, differential analysis, as well as objective and subjective measurement tools of speech quality, namely, Enhanced Modified Bark Spectral Distortion and WideBand Perceptual Evaluation of Speech Quality as the objective measure and Mean Opinion Score and MUltiple Stimuli with Hidden Reference and Anchor as the subjective one. The experimental results proves the robustness of our cryptosystem and its adequacy for real-time secure speech communication.