Efficient traceable oblivious transfer and its applications

Oblivious transfer (OT) has been applied widely in privacy-sensitive systems such as on-line transactions and electronic commerce to protect users\u27 private information. Traceability is an interesting feature of such systems that the privacy of the dishonest users could be traced by the service provider or a trusted third party (TTP). However, previous research on OT mainly focused on designing protocols with unconditional receiver\u27s privacy. Thus, traditional OT schemes cannot fulfill the traceability requirements in the aforementioned applications. In this paper, we address this problem by presenting a novel traceable oblivious transfer (TOT) without involvement of any TTP. In the new system, an honest receiver is able to make a fixed number of choices with perfect receiver privacy. If the receiver misbehaves and tries to request more than a pre-fixed number of choices, then all his previous choices could be traced by the sender. We first give the formal definition and security model of TOT, then propose an efficient TOT scheme, which is proven secure under the proposed security model