Abstract: This paper analyzes the chaotic stream cipher proposed in “Chaos-based secure communication in a large community”, it finds that the frontal values of the encryption sequence of the stream cipher are not sensitive to the least significant bits of the key. So the paper proposes divide-and-conquer attack with known plaintexts and analyses its success probability and complexity. At last, it presents the possible reformative measure of the cipher to its weakness and proves the validity of the measure.

Key words: Chaotic cipher, Chaotic sequence, Divide-and-conquer attack, Adjacent key

摘要： 对Wang Shihong的“Chaos-based secure communication in a large community”一文提出的混沌序列密码算法进行了分析，发现该加密算法产生的加密乱数序列的前若干值对密钥低位比特的变化不敏感。据此利用已知明文攻击，对该算法提出了分割攻击方案，并分析了该攻击方案的成功率和计算复杂性。针对该加密算法存在的弱点给出了可能的改进措施，并证明了其有效性。

关键词: 混沌密码, 混沌序列, 分割攻击, 相近密钥

CLC Number: 

• TP309.7