消息认证码（Message Authentication Codes---MACs）是保证消息完整性的重要工具。Bellare 等人提出了称为XOR-MAC的消息认证码，界定了攻击者成功伪造的概率，从而证明了其安全性，但是他们给出的证明方法较为复杂。本文使用Game-Playing 技术采用新的安全性定义证明了XOR-MAC的安全性，证明方法简单明了；在底层所使用的分组密码是伪随机置换的假设下，量化了该消息认证码与随机函数之间区分的概率。

Message Authentication Codes are very important tools to protect data integrity. XOR-MAC is defined by Bellare, which also give a security analysis for it. But security analysis for XOR-MAC they gave is complex. In this paper, we use Game-Playing technique to give a new security analysis for XOR-MAC. We prove XOR-MAC secure, quantifying an adversary’s success probability of distinguishing XOR-MAC from purely random function in terms of the quality of the block cipher as a pseudorandom permutation.