Oblivious Transfer and Applications

Mihir Bellare Y, Silvio M. Micali

Zhide Chen

Oblivious transfer(OT)is used as a key component in many applications of cryptography. In this paper, a1-out-of-n oblivious transfer is constructed based on the sub protocol 1-out-of-2 oblivious transfer;an m-out-of-n oblivious transfer is constructed based on the sub protocol 1-out-of-n oblivious transfer. Finally,a1-out-of-2 oblivious transfer is constructed based on public key system. By this way,any existed public key system can be used to construct m-out-of-n oblivious transfer.

Christian Tobias

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.

Yael Gertner, Tal Malkin

In this paper, we present a new application for , n 1 oblivious transfer, which i s a n i n teractive protocol between two parties Alice and Bob, where Alice has n secrets and Bob has a query i.A t the end of the protocol Bob has the ith secret and no other information about Alice's other secrets, while Alice does not get any information about i.This new application is the Secure Database Access problem.Motivated by this application, we propose an OT scheme which a c hieves low communication complexity and information theoretic security.We use a distributed model for , n 1 oblivious transfer, where Bob interacts with multiple \Alices".In this model, we base our scheme on any PIR scheme, which i s a s c heme where only the privacy of Bob is considered, and use it to construct an OT scheme, private for both parties, without paying too much i n communication complexity.This results in the rst sublinear information theoretic scheme for , n 1 OT.Further motivated by the application of , n 1 OT for polynomial n, w e raise the issue of repetition in , n 1 OT, where both security and eciency are important.We show that previous protocols for , n 1 oblivious transfer fail in this setting.

Kai Chen, Qiang Yang