Compound Biometric Authentication Systems with Strong Secrecy

In classical biometric authentication systems, the authenticity of each user is determined by comparing two secret-keys which are generated based on the user's biometric enrollment and authentication sequences. These sequences are generated based on the correlated components of a common source whose statistics are assumed to be known. In the compound biometric authentication model in contrast, the statistics of the source are unknown. In this case, the protocol should guarantee the security and reliability of authentication procedure, simultaneously for all realizations of the compound source. In compound biometric authentication setups which have been investigated until now, only the weak secrecy criterion has been guaranteed. In this work, a single-letter secret-key rate versus privacy leakage rate capacity region of the compound biometric authentication system is given for the case where strong secrecy is also guaranteed. It is shown that the capacity regions under both strong and weak secrecy conditions are equivalent.