Rotem Arnon-Friedman: Entropy accumulation in device-independent protocols

Опубликовано 1 февраля 2017, 1:36

"Proving security of device-independent (DI) cryptographic protocols has been regarded a complex and tedious task. The main difficulty consists in analysing how the eavesdropper's uncertainty ``accumulates'' through many repetitions of a basic test, or ``entropy-generating'' block, on which the protocol is based. Previous satisfactory quantitative bounds were restricted to the case where the repetitions are independent, a strong and often unwarranted assumption.

Our main contribution is a general information-theoretic result, the ``entropy accumulation theorem'', which shows that entropy accumulation occurs in quite general settings in which there is no independence assumption. Our theorem is relevant for applications: we give simple and modular security proofs for DI randomness generation and quantum key distribution. For both tasks we establish essentially optimal key rates and noise tolerance. As loophole-free Bell tests are finally being realised, our results considerably decrease the gap between theory and experiments, thereby marking an important step towards practical DI protocols and their implementation."