Private authentication with controllable measurement

Abstract

We consider the problem of secret key-based authentication under a privacy constraint on the enrolled source data. The user's measurement in the authentication phase is assumed to be controllable via a cost-constrained “action” sequence. We provide a single-letter characterization of the optimal tradeoff among the secret key rate, storage rate, leakage rate, and action cost. The result can be relevant for several user-authentication scenarios including hardware-based and biometric authentication with multiple measurements. Moreover, our result includes, as a special case, a new result for secret-key generation with action-dependent side information where there is no privacy constraint on the source sequence.