Authentication and Partial Message Correction over Adversarial Multiple-Access Channels

In this paper, we present results on the authentication capacity region for the two-user arbitrarily-varying multipleaccess channel. We first consider a standard definition of authentication, in which the receiver may discard both messages if an adversary is detected. For this setting, we show that an extension of the arbitrarily-varying channel condition overwritability characterizes the authentication capacity region. We then define γ-correcting authentication, where we require that at least a γ fraction of the users' messages be correctable, even in the presence of an adversary. We give necessary conditions for the γ-correcting authentication capacity region to have nonempty interior, and show that positive rate pairs are achievable over a particular channel that satisfies these conditions.