Universally composable issuer‐free adaptive oblivious transfer with access policy

Abstract

AbstractIn today's Internet world, security, privacy and efficiency are three prime concerns in designing any cryptographic protocol. Adaptive oblivious transfer with access policy (AOT‐AP) is widely used in oblivious search of privacy preserving databases in which each message is associated with an access policy and only authorized receivers can access the databases. All the existing AOT‐AP protocols assume a trusted third party called issuer apart from a sender and multiple receivers and are secure under the restriction that the issuer never colludes with a collection of receivers. We propose the first issuer‐freeAOT‐AP in universal composable (UC) framework. Our issuer‐free AOT‐AP is UC secure under standard assumptions assuming malicious adversary in static corruption model. More interestingly, our scheme exhibits significant improvements over the existing schemes. Copyright © 2015 John Wiley & Sons, Ltd.