A Variant of Naor-Pinkas Oblivious Transfer for More Efficient Authentication

Abstract

Oblivious Transfer(OT) protocol is a fundamental primitive in the modern cryptography. In the realistic unauthenticated setting, we should consider message authentication which is a prime necessity in the information security. It is, however, not considered in general for designing OT protocol because we can provide it in modular way. A shared key is established by authenticated key-exchange(AKE) protocol and used with message authentication code(MAC). By the way, the existing solutions for authentication introduce non-negligible computational overheads such as modular exponentiation. Thus, we have the following question: “Can we build the more efficient authentgnicated OT protocol?” In this work, we show, by presenting an efficient authenticated variant of Naor-Pinkas OT, that it is possible with little costs. We present a conceptually simple and unified primitive that does not require the authenticated channel assumption.