In this paper, a cryptanalysis method that combines a chosen-ciphertext attack with a divide-and-conquer attack by traversing multiple nonzero component initial conditions (DCA-TMNCIC) is proposed. The method is used for security analysis of n-D (n = 3, 4, 5, 6, 7, 8) self-synchronous chaotic stream ciphers that employ a product of two chaotic variables and three chaotic variables (n-D SCSC-2 and n-D SCSC-3), taking 3-D SCSC-2 as a typical example for cryptanalysis. For resisting the combinational effect of the chosen-ciphertext attack and DCA-TMNCIC, several improved chaotic cipher schemes are designed, including 3-D SCSC based on a nonlinear nominal system (3-D SCSC-NNS) and n-D SCSC based on sinusoidal modulation (n-D SCSC-SM (n = 3, 4, 5, 6, 7, 8)). Theoretical security analysis validates the improved schemes.

中文翻译：

---

几种自同步混沌流密码的密码分析及其改进方案

在本文中，提出了一种通过遍历多个非零分量初始条件（DCA-TMNCIC）将选择密文攻击与分而治之攻击相结合的密码分析方法。该方法用于安全性分析n-D (n = 3, 4, 5, 6, 7, 8）自同步混沌流密码，采用两个混沌变量和三个混沌变量的乘积（n-D SCSC-2 和n-D SCSC-3)，以 3-D SCSC-2 作为密码分析的典型例子。为了抵抗选择密文攻击和 DCA-TMNCIC 的组合效应，设计了几种改进的混沌密码方案，包括基于非线性标称系统的 3-D SCSC（3-D SCSC-NNS）和n-D SCSC 基于正弦调制 (n-D SCSC-SM (n = 3, 4, 5, 6, 7, 8））。理论安全分析验证了改进的方案。