一种挖掘低速率语音编码最低有效位的新方法

摘要

Information hiding is an important means to ensure the security of information transmission.In view of the difficulty of locating the least significant bit of low-rate speech code in VOIP system when hiding information,we use genetic algorithm as the optimisation tool and construct the objective function of genetic algorithm according to the objective evaluation criterion of speech quality and the capacity of information hiding,as well as propose a new method which can mine the least significant bit of low-rate speech code.Experimental tests have been carried out on the example of G.729a speech code,test results show that the method can accurately determine all the least significant bits with the object of maximising the information hiding capacity under the given voice quality.Finally the feasibility of information hiding technique is verified by the covert transmission of confidential information in least significant bit of speech frame.%信息隐藏是保证信息传输安全的重要手段。针对 VOIP 系统中低速率语音编码在信息隐藏时最低有效位难以确定的问题，利用遗传算法 GA（Genetic Algorithm）作为优化工具，以客观的语音质量评价标准和信息隐藏容量为依据构建遗传算法目标函数，提出一种能够挖掘低速率语音编码最低有效位的新方法。以 G．729a 语音编码为例进行实验测试，测试结果表明，该方法在给定的语音质量下，以隐藏容量最大为目标可以精确搜索到所有最低有效位。最后通过在语音帧的最低有效位上进行机密信息的隐秘传输验证信息隐藏技术的可行性。