| 一类混沌流密码的分析 |
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| 引用本文： | 李树钧,牟轩沁,纪震,张基宏.一类混沌流密码的分析[J].电子与信息学报,2003,25(4):473-478. |
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| 作者姓名： | 李树钧 牟轩沁 纪震 张基宏 |
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| 作者单位： | 1. 西安交通大学电子与信息工程学院,西安,710049
2. 深圳大学信息工程学院,深圳,518060 |
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| 摘 要： | 该文指出一类基于数字化逐段线性混沌映射的混沌流密码方案是不够安全的．在有限数字精度下，分段线性混沌映射存在可度量的特征退化，这种退化由控制参数所在的参数空间子集唯一决定．由此可以推知，在已知明文的情况下，整个密钥空间可以分解为强度依次降低的弱密钥子空间．在此基础上可以导出一类多分辨率攻击方法，在密钥随机分配的情况下，该攻击方法从总体上可以把密钥熵降低2bit．试验结果表明，该文提出的多分辨率攻击方法是实际可行的．该文还讨论了一些可能采取的改进措施及其效果。
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| 关 键 词： | 混沌流密码 多分辨率 弱密码 PLCM |
| 收稿时间： | 2001-12-17 |
| 修稿时间： | 2001年12月17 |
Cryptanalysis of a class of chaotic stream ciphers |
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| Li Shujun,Mou Xuanqin,Ji Zhen,Zhang Jihong.Cryptanalysis of a class of chaotic stream ciphers[J].Journal of Electronics & Information Technology,2003,25(4):473-478. |
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| Authors: | Li Shujun Mou Xuanqin Ji Zhen Zhang Jihong |
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| Affiliation: | School of Electron and Info. Eng.,Xi an Jiaotong University Xi an 710049 China;Faculty of Information Engineering Shenzhen University Shenzhen 518060 China |
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| Abstract: | This paper points out that a class of chaotic stream ciphers proposed recently is not secure enough, which is based on digital Piecewise Linear Chaotic Maps (PLCM). It has been known that digital PLCMs' statistical properties have essential degradation when PLCMs are realized in finite computing precision, and that such degradation is determined by the resolution of the control parameter (i.e., determined by which digital subset the control parameter is in). Hence, for the studied chaotic stream ciphers, the whole key space can be divided into n - 1 sub-spaces with incremental weakness degree, and the weakness of any fixed key cannot be improved by using higher precision. Based on the above fact, a kind of multi-resolution cryptanalysis is presented to attack the chaotic ciphers. When secure key is selected randomly, the key entropy will decrease by 2bit as a whole. Experiments show that this cryptanalysis is feasible and efficient. |
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| Keywords: | Chaotic stream cipher PLCM Cryptanalysis Weak key Multi-resolution |
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