一、引言无疑,加密算法在一个密码系统中(及其它有关的密码应用中)起着核心作用。当然要保证一个系统是安全的,单有好的加(解)密算法是不够的,还需要相应的密钥管理措施和好的运用加密算法的技术等等,但一个弱的加密算法肯定是不安全的。而对一个加密算法来说,最重要的指标就是在现有技术条件下对其作密码分析攻击所要求的时间、空间上的开销。在计算机科学中,一个算法通常是指一个有穷规则的集合,这些规则规定了求解某特 I. INTRODUCTION There is no doubt that encryption algorithms play a central role in a cryptographic system (and other related cryptographic applications). Of course, to ensure that a system is safe, a good solution to (secret) secret algorithm is not enough, but also the corresponding key management measures and good use of encryption algorithm technology, etc., but a weak encryption algorithm is certainly unsafe. For an encryption algorithm, the most important indicator is the time and space required for cryptanalytic attacks under the existing technical conditions. In computer science, an algorithm usually refers to a collection of finite rules that specify the solution of a particular