话音信号加密的剩余可懂度分析

话音加密信号的剩余可懂度是话音加密系统的重要技术指标之一，加密系统必须将电话加密信号中原语音信号的剩余可懂度减至最小。采用软件模拟分析方式，对不同话音加密处理后话音信号的剩余可懂度进行分析，并通过录音机播放形式进行实验和测试，结果表明同步模数模时比特掩盖加密体制的保密度取决于密钥序列的随机性。随机性愈好，保密性就愈好。

The Residual Intelligibility Analysis for Enciphered Speech Signal

The residual intelligibility for enciphered speech signal is one of the important characteristics in speech encryption system.It is necessary to decrease the residual intelligibility as small as possible for any encryption system.In this paper we analyse the residual intelligibilities of a speech signal in different encipher methods with software analogue,and then make the experiments and the checks by recording and playing the enciphered signal.