摘要： IDEA是一个著名的加密算法，被广泛运用于各种领域，最著名的有PGP。该文介绍了IDEA算法，并分析了IDEA算法存在弱密钥的原因，研究设计并实现了变长密钥的IDEA算法。该算法理论上可使密钥长度达到无限长，抗攻击能力最大可达到2832的计算量，极大地加强了该算法的安全性，同时消除了标准IDEA算法存在的弱密钥，最后还对该算法的时间复杂度、抗攻击能力等进行了分析。

关键词: IDEA算法, 变长密钥, 弱密钥, 对称密钥

Abstract: The international data encryption algorithm is a well-known cryptosystem that is wildly used in various fields, such as PGP, but large classes of weak keys have been found in the block cipher algorithm. The paper first analyzes the cause for weak keys in IDEA, and further offers an improved algorithm of the variable length keys. The improved algorithm,in theory, enables the length of keys to reach infinity, and the ability of defense to the maximum of 2832. Meanwhile, it solves the problem of the weak keys in standard IDEA. Last, this paper analyzes the efficiency, the defensive ability, etc. of the improved algorithm.

中图分类号: 

• TP393.08