一种混沌映射密码算法的安全性分析

Cryptanalysis on the Cryptography of the Chaotic Maps

近年来有许多基于迭代混沌映射的密码系统被提出,但它们中很少能抵抗选择明文攻击、选择密文攻击或者已知明文攻击。本文分析了参考文献[14]中存在的一些缺陷并且攻破它。参考文献[14]主要思想在于使用变长扩展密钥(最大128位)构造四个一维混沌映射的初值和迭代次数,获取初值和迭代次数的过程是有限整数问题,存在致命缺陷,不具抗攻击性,本文使用选择密文/明文攻击方法在很短时间内就能恢复变长扩展密钥。

Recently many chaotic cryptosystems based on the iterative equation have been proposed,but many of them can’t resist the chosen ciphertext attack,chosen plaintext attack and known plaintext attack.In this letter,we analyze the existing problems of cryptography using multiple one-dimensional chaotic maps [14] presented by Pareek et al.and break it.This cryptosystem uses an external secret key of variable length（maximum 128-bits）to obtain the initial condition and number of iterations of four one-dimensional chaotic maps,but this way exists weaknesses of deriving the initial condition by using finite integer problem allowing for attack.So,the external secret key of variable length can be recovered with a little time using the chosen ciphertext attack or chosen plaintext attack.