Privacy, Secrecy, and Storage with Multiple Measurements of Noisy Identifiers

The key-leakage-storage capacity regions for a hidden biometric or physical identifier’s noisy measurements at two terminals of a secrecy system are derived. The capacity regions of binary hidden sources with multiple decoder measurements are obtained by applying Mrs. Gerber’s lemma twice in different directions to a Markov chain to show gains in the privacy-leakage rate as compared to assuming a noise-free identifier at the encoder and to depict possible secrecy leakage if the noise-free identifier assumption is not true. The enlargement of the capacity region by increased number of decoder measurements is illustrated. The privacy-leakage rate is shown to be particularly small if a key is generated by measuring the hidden source a large number of times at the decoder. The gain in the maximum secret-key rate at the cost of higher privacy-leakage and storage rates with increased number of encoder measurements is also illustrated. (Joint work with Gerhard Kramer)

Onur Günlü  (S’10) received the B. Sc. degree in Electrical and Electronics Engineering from Bilkent University, Ankara, in 2011, and the M. Sc. degree in Communications Engineering from the Technical University of Munich (TUM), Munich, in 2013. He is currently pursuing the Dr.-Ing. degree at the Institute for Communications Engineering at the TUM under the supervision of Prof. Gerhard Kramer. His research interests include information-theoretic security, algorithm and code design for biometric secrecy systems and physical unclonable functions (PUFs).