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.

传统密码系统由于其较小的密钥空间而不能满足当前的某些安全要求，因此并不适合所有情况，这使得它们很容易受到暴力攻击，并且由于时间复杂度高而在实时应用中效率低下。近来，诸如基于超混沌的语音信号的安全应用成为研究的焦点。它们的特性（如不可预测性和随机性）使它们成为数据保护的有效替代方案。本文介绍了一种基于Lorenz系统的新型4D超混沌密码系统，方法是在其经典方程式中添加一个新状态，以对使用AMR-WB G.722.2编解码器编码的语音进行完全和部分加密。为了提高计算安全性，我们通过结合混淆和扩散机制来执行加密，为了评估我们提出的密码系统方案的效率，我们在波形和频谱图分析，灵敏度分析，键空间分析，统计分析，差分分析以及语音质量的主观和主观测量工具的基础上进行了几次实验，即，以改进的吠声频谱失真和语音质量的宽带感知评估为客观指标，以平均参考分数和多重刺激为基础的隐性参考和锚定为主观评价。实验结果证明了我们的密码系统的鲁棒性及其对于实时安全语音通信的充分性。语音质量的统计分析，差异分析以及客观和主观的测量工具，即增强的改进树皮频谱失真和语音质量的宽带感知评估作为客观度量，平均意见得分和多重刺激（采用隐藏参考和锚定）主观的一个。实验结果证明了我们的密码系统的鲁棒性及其对于实时安全语音通信的充分性。语音质量的统计分析，差异分析以及客观和主观的测量工具，即增强的改进树皮频谱失真和语音质量的宽带感知评估作为客观度量，平均意见得分和多重刺激（采用隐藏参考和锚定）主观的一个。实验结果证明了我们的密码系统的鲁棒性及其对于实时安全语音通信的充分性。