Device independent oblivious transfer works despite quantum device faults
Robust and leakage-resilient device-independent oblivious transfer in MiniQCryp
Cryptography and Security
Summary
Oblivious transfer is a way for two parties to share information securely, but usually it needs trusted devices. This paper shows how to do it even if the quantum devices used might be faulty or poorly behaving, using only trusted classical computers to operate them. Their method protects against attackers with quantum computers and can handle some device errors or information leakage. It builds on complex quantum game theory ideas to ensure security and can be used to do many secure multiparty computations on classical data without trusting the quantum devices fully.
What this means in practice
- •For blockchain developers: Create multiparty protocols that remain secure even when quantum sources or devices cannot be fully trusted or may leak information.
- •For secure software engineers: Implement classical cryptographic protocols relying on oblivious transfer with built-in security against quantum device flaws or side-channel leakages.
Authors
Zhili Chen, Rahul Jain, YaoNan Zhang
Abstract
Assuming post-quantum one-way functions, we construct device-independent (DI) oblivious transfer (OT) and bit commitment: honest parties use only trusted classical computation to operate untrusted quantum devices, which may share arbitrary entanglement and behave non-IID. Security is simulation-based against quantum polynomial-time adversaries and composes sequentially with efficient simulators. One protocol skeleton serves both, in two regimes. With isolated laboratories and coordinate-local measurements in the honest receiver's device, it tolerates a constant rate of honest-device faults. With polylogarithmically many qubits of adaptive leakage between the laboratories and arbitrary joint measurements, it tolerates an inverse-polylogarithmic rate. Each elementary DI call uses a fresh, isolated batch of polylogarithmically many device coordinates, and total device use in the compiled OT protocol is polynomial. The commitment has efficient simulators against both parties and yields DI coin tossing with abort. Because OT is complete for secure computation, the construction yields a DI protocol, with abort, for every efficiently computable classical functionality on a fixed number of parties, secure against static corruption of any proper subset of them. The commitment's extractor changes a public parity relation through classical equivocation and leaves the device execution, hence its leakage, unchanged. A commit-and-prove functionality, disjoint audits, and an affine consistency check link the certified correlations to ideal OT. Sender security rests on a selector-aware parallel-repetition bound for the Magic Square game, which we derive from the two-round threshold theorem of Kundu and Tan.