Abstract: A new structure is presented for stream cipher. The stream cipher Salsa20 is improved based on the new structure. The results show that the improved algorithm can resist slide attack efficiently as the slid pairs are reduced from 2²⁵⁶ to 0. Furthermore the improved algorithm can resist 2nd preimage attack and differential cryptanalysis. The improved stream cipher doesn't change the encryption speed, which has been tested experimentally.

Key words: stream cipher, Salsa20, slide attack, 2nd preimage attack, differential attack

摘要： 提出了一种新的流密码算法设计结构, 并基于此结构对流密码算法 Salsa20 进行改进。分析结果表明, 改进后算法的滑动对个数从2256 降为0, 能有效抵抗滑动攻击, 并能更好地抵抗第二原象攻击和差分攻击。实验结果表明, 改进算法的软件实现速度基本保持不变。

关键词: 流密码, Salsa20, 滑动攻击, 第二原象攻击, 差分攻击