Information Security Seminar 

03/05/2013, 16:15 — 17:15 — Room P3.10, Mathematics Building
Paulo Mateus, SQIG-IT / IST-UTL

Improving classical authentication over a quantum channel

We introduce a quantum protocol to authenticate classical messages that can be used to replace Wegman-Carter's classical authentication scheme in quantum key distribution (QKD) protocols. We show that the proposed scheme achieves greater conditional entropy of the seed for the intruder given her (quantum) observation than the classical case. Our protocol is an improvement over a classical scheme by Brassard, taking advantage of quantum channel properties. It is motivated by information-theoretical results. However by adopting it, QKD becomes a fully quantum protocol. We prove that quantum resources can improve both the secrecy of the key generated by the PRG and the secrecy of the tag obtained with a hidden hash function. We conclude that the proposed quantum encoding offers more security than the classical scheme and, by applying a classical result, we show that it can be used under noisy quantum channels. Joint work with F. Assis, A. Stojanovic and Y. Omar.