On the Security of the Quantum Oblivious Transfer and Key Distribution Protocols

雅一 吉田

Mariana F. Ramos, Michael Hentschel, Federico Valbusa +7 more

We present an experimentally feasible implementation of a secure multiparty computation application enabled by quantum oblivious transfer (QOT) on an entanglement-based physical layer. The QOT protocol uses polarization-encoded entangled states to share oblivious keys between two parties with quantum key distribution (QKD) providing authentication. Our system integrates the post-processing for QOT and QKD, both sharing a single physical layer, ensuring efficient key generation and authentication, respectively. Authentication involves hashing messages into a cryptographic context, verifying tags, and replenishing keys. This process uses a parallel QKD pipeline specifically for authentication, not for secure key generation. Oblivious keys are generated over a distance up to 25.8 km with a channel loss of 8.47 dB. In a back-to-back setup, a QOT rate of [Formula: see text] OTs/second is achieved, corresponding to 1 minute and 53 seconds per OT, primarily limited by the entanglement source. Using pre-distributed oblivious keys improved the rate to 0.11 OTs/second, or 9.1 seconds per OT. The considered QOT protocol is statistically correct, computationally secure for an honest receiver, and statistically secure for an honest sender, assuming a computationally hiding, statistically binding commitment. An experimentally feasible use case is demonstrated for privacy-preserving fingerprint matching against no-fly lists for border control. The fingerprint is secret-shared across two sites, ensuring security, while the matching is performed using the MASCOT protocol, supported by QOT. The application required 128 1-out-of-2 OTs, each with message length of 128 bits, with the highest security achieved in 20 minutes and 39 seconds. This work demonstrates the feasibility of QOT in secure quantum communication applications.

Víctor Zapatero

Shu–Yu Kuo, Kuo-Chun Tseng, Yao–Hsin Chou +1 more

In cryptography, oblivious transfer (OT) is an important multi-party cryptographic primitive and protocol, that is suitable for many upper-layer applications, such as secure computation, remote coin-flipping, electrical contract signing and exchanging secrets simultaneously. However, some no-go theorems have been established, indicating that one-out-of-two quantum oblivious transfer (QOT) protocols with unconditional security are impossible. Fortunately, some one-out-of-two QOT protocols using the concept of Crépeau’s reduction have been demonstrated not to conform to Lo’s no-go theorem, but these protocols require more quantum resources to generate classical keys using all-or-nothing QOT to construct one-out-of-two QOT. This paper proposes a novel and efficient one-out-of-two QOT which uses quantum resources directly instead of wasting unnecessary resources to generate classical keys. The proposed protocol is not covered by Lo’s no-go theorem, and it is able to check the sender’s loyalty and avoid the attack from the receiver. Moreover, the entangled state of the proposed protocol is reusable, so it can provide more services for the participants when necessary. Compared with other QOT protocols, the proposed protocol is more secure, efficient, and flexible, which not only can prevent external and internal attacks, but also reduce the required resources and resource distribution time.

Mariano Lemus, Mariana F. Ramos, Preeti Yadav +6 more

The oblivious transfer primitive is sufficient to implement secure multiparty computation. However, secure multiparty computation based on public-key cryptography is limited by the security and efficiency of the oblivious transfer implementation. We present a method to generate and distribute oblivious keys by exchanging qubits and by performing commitments using classical hash functions. With the presented hybrid approach of quantum and classical, we obtain a practical and high-speed oblivious transfer protocol. We analyse the security and efficiency features of the technique and conclude that it presents advantages in both areas when compared to public-key based techniques.

Eli Biham, Michel Boyer, P. Oscar Boykin +2 more