Paper 2010/509

On Efficient Non-Interactive Oblivious Transfer with Tamper-Proof Hardware

Maria Dubovitskaya, Alessandra Scafuro, and Ivan Visconti

Abstract

Oblivious transfer (OT, for short) [RAB81] is a fundamental primitive in the foundations of Cryptography. While in the standard model OT constructions rely on public-key cryptography, only very recently Kolesnikov in [KOL10] showed a truly efficient string OT protocol by using tamper-proof hardware tokens. His construction only needs few evaluations of a block cipher and requires stateless (therefore resettable) tokens that is very efficient for practical applications. However, the protocol needs to be interactive, that can be an hassle for many client-server setting and the security against malicious sender is achieved in a covert sense, meaning that a malicious sender can actually obtain the private input of the receiver while the receiver can detect this malicious behavior with probability 1/2. Furthermore the protocol does not enjoy forward security (by breaking a token one violates the security of all previously played OTs). In this work, we propose new techniques to achieve efficient non-interactive string OT using tamper-proof hardware tokens. While from one side our tokens need to be stateful, our protocol enjoys several appealing features: 1) it is secure against malicious receivers and the input privacy of honest receivers is guaranteed unconditionally against malicious senders, 2) it is forward secure, 3) it enjoys adaptive input security, therefore tokens can be sent before parties know their private inputs. This gracefully fits a large number of client-server settings (digital TV, e-banking) and thus many practical applications. On the bad side, the output privacy of honest receivers is not satisfied when tokens are reused for more than one execution.

Note: This version includes an updated comparison with related work and points out some output-privacy issues of our construction.