UC Priced Oblivious Transfer with Purchase Statistics and Dynamic Pricing

Abstract

Priced oblivious transfer (POT) is a cryptographic protocol that can be used to protect customer privacy in e-commerce applications. Namely, it allows a buyer to purchase an item from a seller without disclosing to the latter which item was purchased and at which price. Unfortunately, existing POT schemes have some drawbacks in terms of design and functionality. First, the design of existing POT schemes is not modular. Typically, a POT scheme extends a k-out-of-N oblivious transfer (OT) scheme by adding prices to the items. However, all POT schemes do not use OT as a black-box building block with certain security guarantees. Consequently, security of the OT scheme needs to be reanalyzed while proving security of the POT scheme, and it is not possible to swap the underlying OT scheme with any other OT scheme. Second, existing POT schemes do not allow the seller to obtain any kind of statistics about the buyer’s purchases, which hinders customer and sales management. Moreover, the seller is not able to change the prices of items without restarting the protocol from scratch.