对自同步混沌密码的分割攻击方法

A Divide-and-Conquer Attack on Self-Synchronous Chaotic Ciphers

本文分析了自同步混沌密码的信息泄漏规律,并据此提出了对自同步混沌密码的分割攻击方法.由于能够利用所有时刻的已知明文进行攻击,因而自同步混沌密码比同步混沌密码的抗分割攻击能力更弱.本文以Hong Zhou等提出的自同步混沌密码为例,完成了对密钥规模为64比特且以混沌映射的65次迭代为自同步映射的自同步密码的分割攻击.利用1万个已知明文,在主频为2.5GHz的Pentium-4 PC上,攻击的平均时间为25小时22分,成功率为0.86.

In this paper the authors analysis the law of information leak of self-synchronous chaotic ciphers, hereby present a divide-and-conquer attack to self-synchronous chaotic ciphers, which is the first attack of this kind in this area. Because the output signals at each clock can be used in the attack, the ability of self-synchronous chaotic ciphers to resist the divide-and-conquer attack is weaker than that of synchronous chaotic ciphers. As an example, we realized the divide-and-conquer attacks to the self-synchronous chaotic cipher proposed by Hong Zhou etc. with 64 bits key and the self-synchronous chaotic map being the 65 iterations of a chaotic map. It took about 25 hours and 22 minutes to recover the key at a success rate 0.86 on a Pentium 4/2.5GHz personal computer with 10000 known plaintext.