In collaboration with Princeton University
A. Bunin, Z. Goldfeld, H. H. Permuter, S. Shamai, P. Cuff and P. Piantanida
In Proceedings of the 2nd Workshop on Communication Security affiliated with EUROCRYPT, Paris, France, April 2017
We study the trade-off between secret message (SM) and secret key (SK) rates, simultaneously achievable overa state-dependent (SD) wiretap channel (WTC) with non-causal channel state information (CSI) at the encoder. Thismodel subsumes other instances of CSI availability as special cases, and calls for efficient utilization of the statesequence for both reliability and security purposes. An inner bound on the semantic-security (SS) SM-SK capacityregion is derived based on a superposition coding scheme inspired by a past work of the authors. The region isshown to attain capacity for a certain class of SD-WTCs. SS is established by virtue of two versions of the strongsoft-covering lemma. The derived region yields an improvement upon the previously best known SM-SK trade-offresult reported by Prabhakaran et al., and, to the best of our knowledge, upon all other existing lower bounds foreither SM or SK for this setup, even if the semantic security requirement is relaxed to weak secrecy. It is demonstratedthat our region can be strictly larger than those reported in the preceding works.