An e-Coin Based Construction for Unlinkable Priced Oblivious Transfer

A '1-out-of-n' oblivious transfer (OT) protocol involves two participants: a sender, who provides a set of items as input, and a receiver. The protocol guarantees that the receiver gets exactly one of the items of the input set, while the sender is unable to determine which. Priced OT (POT) protocols further allow each item of the input set to be assigned a price in such a way that, after a proper execution of the protocol, the receiver gets the requested item if and only if the corresponding sum of money has been paid. In this paper, we present a construction which takes a '1-out-of-n' OT protocol and transform it into a POT one. Moreover, the resulting system is unlinkable in the sense that the sender is unable to determine whether two executions of the protocol were run by the same receiver or not. When compared to existing unlinkable POT protocols, our construction offers a lower conceptual complexity as it does not involve the use of zero-knowledge proofs.