In both open and private communication the participants face potential threats from a malicious enemy who has access to the communication channel and can insert messages (impersonation attack) or alter already transmitted messages (substitution attack). Authentication codes (A-codes) have been developed to provide protection against these threats. In this paper we introduce a new distance, called the authentication distance (A-distance), and show that an A-code can be described as a code for the A-distance. The A-distance is directly related to the probability P/sub S/ of success in a substitution attack. We show how to transform an error-correcting code into an A-code and vice versa. We further use these transformations to provide both upper and lower bounds on the size of the information to be authenticated, and study their asymptotic behavior. As examples of obtained results, we prove that the cardinality of the source state space grows exponentially with the number of keys provided P/sub S/
展开▼
机译：在公开和私人通信中，参与者都面临来自恶意敌人的潜在威胁，该恶意敌人可以访问通信通道并可以插入消息（模拟攻击）或更改已传输的消息（替代攻击）。已经开发出认证代码（A代码）以提供针对这些威胁的保护。在本文中，我们介绍了一个新的距离，称为身份验证距离（A距离），并表明可以将A代码描述为A距离的代码。 A距离与替换进攻中成功的概率P / sub S /直接相关。我们展示了如何将纠错码转换为A码，反之亦然。我们进一步使用这些转换来提供要验证的信息大小的上限和下限，并研究它们的渐近行为。作为获得结果的示例，我们证明了源状态空间的基数随提供的键数P / sub S /
