序列密码的安全保密性主要依赖于密钥序列，因此研究什么样的伪随机序列可以作为序列密码的密钥序列就成为序列密码研究中的主要问题，即序列密码的关键是产生密钥序列的算法。-Security and confidentiality of the password depends on the sequence of key sequence, the study of what can be used as a pseudo-random sequence key sequences password becomes a stream cipher research main issues, namely key sequence is generated password key sequence algorithm.