Universally Composable Priced Oblivious Transfer

In this work we further enhance the work of Aiello et al. [1] on priced oblivious transfer, in which selling digital goods based on oblivious transfer is discussed. Their primary goal is to mimic a scenario in which a customer is buying digital goods from the vendor where the privacy of the customer is fully protected regarding which item(s) are bought or what is the total amount of shopping. Nevertheless, they make sure that the vendor obtains his money, and as long as the buyer has sufficient balance, he can continue shopping and the price of the bought items will be withdrawn from his balance. They try to avoid zeroknowledge proofs and hence keeping communication cost very low. We propose two different structures for this protocol in order to execute it concurrently over the universal composability framework. In the proposed schemes, we try to keep communication cost as low as possible.