Controllable Identifier Measurements for Private Authentication with Secret Keys

TL;DR

This paper characterizes the optimal trade-offs among secret-key rate, storage, privacy leakage, and action cost in privacy-constrained authentication systems using controllable identifier measurements, applicable to biometric and physical authentication scenarios.

Contribution

It provides single-letter characterizations of these trade-offs for systems with noisy or noiseless measurements, extending to new cases of secret-key generation and embedding with action-dependent side information.

Findings

Derived optimal trade-offs among key rate, storage, privacy, and action cost.

Extended results to secret-key generation with action-dependent side information.

Applicable to biometric and physical authentication scenarios.

Abstract

The problem of secret-key based authentication under a privacy constraint on the source sequence is considered. The identifier measurements during authentication are assumed to be controllable via a cost-constrained "action" sequence. Single-letter characterizations of the optimal trade-off among the secret-key rate, storage rate, privacy-leakage rate, and action cost are given for the four problems where noisy or noiseless measurements of the source are enrolled to generate or embed secret keys. The results are relevant for several user-authentication scenarios including physical and biometric authentications with multiple measurements. Our results include, as special cases, new results for secret-key generation and embedding with action-dependent side information without any privacy constraint on the enrolled source sequence.