中文摘要：

混沌密码学是密码学的一个新方向，混沌序列的复杂度是衡量混沌密码学安全性的重要指标。本文将小波包能量熵应用到混沌序列的复杂度分析中，首先将混沌序列进行小波包分解，然后通过小波包能量熵计算方法确定各频段能量大小，从而确定混沌序列的复杂度。通过对 Logistic、TD-ERCS 和 Henon 产生的混沌序列进行比较分析，结果表明，小波包能量熵具有全局统计特性，无需引入新参数进行相空间重构。另外，计算方法简单，且不依赖于混沌序列的采样长度与初始值，能有效衡量混沌序列的复杂度。

英文摘要：

Chaotic cryptography is a new direction of cryptography,and chaotic sequence complexity is an important index to measure the security of chaotic cryptography.The wavelet packet energy entropy is discussed in this paper to analyze the complexity of chaotic sequence.Firstly,chaotic sequences are decomposed by wavelet packet,and then each frequency band’s energy can be computed with wavelet energy entropy calculation method.Thus the complexity of chaotic sequences is finally determined.Compar-ing the chaotic sequences generated by Logistic,TD-ERCS and Henon,we can discover that the wavelet packet energy entropy has the global statistical property,which doesn’t require new parameters for phase space reconstruction.In addition,its calculation method is simple and it does not rely on the chaotic sequence’s sampling length and initial values,which can effectively measure the complexity of chaotic sequences.