Stream Cipher System Based on Chaotic Binary Sequences

流密码提供了可能是最重要的现代加密方法。流密码学的核心问题是难以有效地从短而随机的密钥中生成长而不可预测的二进制信号序列。虽然这种不可预测的序列可以通过各种方式产生，但几乎所有方法都采用线性反馈移位寄存器（LFSR）序列。在本研究中，我们给出了一种不使用这种序列的简单方法来获得使用非线性映射混沌轨道的流密码系统的运行密钥序列。定义了两类平衡二元随机变量序列，分别是混沌二值序列和混沌位序列，它们都是由非线性映射生成的混沌实值轨道得到的。本文提出的流密码系统具有以下特点：1)有多个参数作为短密钥；2)周期为N的运行密钥序列的线性复杂度几乎等于N/2； 3)密文的相关性与DES和FEAL一样好。

Stream ciphers provide probably the most important method of modern encipherment. The central problem in stream cipher cryptography is the difficulty of efficiently generating long unpredictable sequencers of binary signals form a short and random key. Although such an unpredictable sequence can be generated in various ways, linear feedback shift register (LFSR) sequences are employed in nearly all the methods. In this study, not using such sequences, we give a simple method to obtain a running key sequence of stream cipher system in which chaotic orbits of nonlinear maps are used. Two type of sequences of balanced I. I. D. (dependent and identically distributed) binary random variables have been defined, referred to as a chaotic binary sequence and a chaotic bit sequence, each of which is obtained from chaotic real-valued orbits generated by nonlinear maps. The stream cipher system proposed in this study has the following characteristics : 1) There are several parameters as short secret key : 2) The linear complexity of the running-key sequence of period N is nearly equal to N/2 : 3) The correlation property of ciphertexts is as good as those of the DES and FEAL.