Protocols for Authenticated Oblivious Transfer

Oblivious transfer (OT) is a basic building block in many cryptographic protocols. A common approach in designing secure multiparty computation protocols is to assume that messages of the protocol are being transmitted over an authenticated channel, where entities have been authenticated to each other before the actual flows of the protocol. However, the mentioned aspect leads to some restrictions in design and development of secure multiparty computations. In this paper, we exploit some well-known authenticated Diffie-Hellman-based key exchange protocols to build three authenticated 1-out-of-2 oblivious transfer protocols. As a result, our schemes incorporate the authentication within the oblivious transfer protocol itself, instead of performing authentication via a separate sub-protocol. We show that the proposed protocols are secure in the semi-honest model. We also compare our new schemes with the previous methods (performing authentication via a separate sub-protocol) which illustrates that our schemes decrease computational and communication complexity for both sender and receiver.