Abstract: The security of stream cipher is mainly dependent on the randomness degree of the secret key stream. How to design key stream with perfect randomness turns into the main problem. This paper considers some properties of block ciphers such as DES and RC5, in which there are some favorable nonlinear generating methods. It designs a new algorithm to generate a pseudo-random sequence. The randomness of the sequence is analyzed. The result indicates that the algorithm is safe.

Key words: Stream cipher, RC5 algorithm, S-box, DES algorithm, Block cipher

摘要： 流密码的安全性主要取决于密钥流的随机程度，如何构造随机性良好的密钥序列成为流密码所要研究的首要问题。该文借鉴已有的一些分组密码，如DES﹑RC5等设计中的某些产生良好非线性的方法，提出了一种产生伪随机密钥的方法，并对它们的随机性进行了理论分析。分析结果表明，该算法具有良好的安全性。

关键词: 流密码, RC5算法, S盒, DES算法, 分组密码

CLC Number: 

• TP301.6