On the Power of Two-Party Quantum Cryptography

Abstract

We study quantum protocols among two distrustful parties. Under the sole assumption of correctness - guaranteeing that honest players obtain their correct outcomes - we show that every protocol implementing a non-trivial primitive necessarily leaks information to a dishonest player. This extends known impossibility results to all non-trivial primitives. We provide a framework for quantifying this leakage and argue that leakage is a good measure for the privacy provided to the players by a given protocol. Our framework also covers the case where the two players are helped by a trusted third party. We show that despite the help of a trusted third party, the players cannot amplify the cryptographic power of any primitive. All our results hold even against quantum honest-but-curious adversaries who honestly follow the protocol but purify their actions and apply a different measurement at the end of the protocol. As concrete examples, we establish lower bounds on the leakage of standard universal two-party primitives such as oblivious transfer.

28 pages, v2: major revision in presentation of results, some simplified proofs. Appeared at ASIACRYPT 2009

References in corpus (5)

• Reexamination of Quantum Bit Commitment: the Possible and the Impossible
• The Impossibility Of Secure Two-Party Classical Computation
• Single-shot Quantum State Merging
• Quantum weak coin flipping with arbitrarily small bias
• A large family of quantum weak coin-flipping protocols

Cited by in corpus (3)

• Secure Multi-Party Computation with a Dishonest Majority via Quantum Means
• The Quantum Cut-and-Choose Technique and Quantum Two-Party Computation
• Optimal bounds for semi-honest quantum oblivious transfer