非线性滤波器信息泄漏的关键问题研究

非线性滤波器在现代密码系统设计中被广泛采用,因而研究其密码学性质对提高密码设计和分析水平有重要意义.介绍了现代密码体制中使用的布尔函数应满足的性质;定义了扩张函数和扩张谱,定义了非线性滤波器的信息泄漏度;分析了非线性滤波函数输出序列泄漏输入序列信息的关键原因,设计了一种基于信息泄漏的非线性滤波器的攻击方法,该方法还可用于攻击使用了非线性滤波器的密码算法;最后用一个实例说明了如何使用该方法进行攻击.

Research on the Information Leak of Nonliearly Filtered Generator

Nonlinearly Filtered Generators are widely used in modern cryptosystems, and it is remarkably significant to study its cryptographical properties for cryptography and cryptanalysis. The properties of Boolean functions were introduced, Expansion Function and Expansion Spectrum were defined, and the measure of information leak of Nonlinear Filtered Generator was given. The key causation that the output sequence of Nonlinearly Filtered Generator leaks the information of its input sequence was brought out. An attack based on the information leak of the Nonlinearly Filtered Generator was put forward. This method could be used to attack those cryptographic algorithms using Nonlinear Filtered Generator as a part of pseudo random sequence generator. An example was proposed to show how to determine the inputs of Nonlinearly Filtered Generator when its outputs was given.