广义自缩序列的FBDD攻击

FBDD Attack of Generalized Self-shrinking Sequences

流密码是加密体制中的一种重要体制,一直是军事、政府等敏感部门加密的主要手段,近年来在新一代移动通信中占有主流地位。其安全性主要依赖于密钥流序列的安全。基于LFSR的构造是密钥流构造中最为常见的一种。针对基于单个LFSR的广义自缩序列,提出了一种FBDD攻击。该攻击基于BDD攻击,充分利用了BDDs对布尔函数操作上的优良特性。算法分析表明,其时间复杂度是理想的,但是其所需的内存空间较大,有待于进一步的改进。

Stream ciphers,an important class of encryption algorithms,which always have been the major means of encryption for departments sensitive to security,such as military and governments.Recently,they play a primacy guide role in the new generation mobile communication.The security of stream ciphers mainly depend on design of keystream generators,and the generators to be LFSR based is the most common.In this paper,an attack called FBDD is proposed,applied to generalized self-shrinking sequence which is based on single LFSR.The idea of FBDD is motivated by BDDs attack,the good characteristics of BDDs acting on the boolean function is considered.It is showed that the attack has a lower bounds and a large memory,which remains to be further improved in the further work.