A Provably Secure t-out-of-n Oblivious Transfer Mechanism based on Blind Signature.

Jianhong Zhang, Yumin Wang

Richard J. Berger, René Peralta, Tom Tedrick

Matthew Green, Susan Hohenberger

Jing Qin, Jiankun Hu, Huawei Zhao

Oblivious Transfer protocol (OTP) is a paramount important primitive tool in modern cryptography. Essentially, OTP can be used to construct a secure multi-party computation protocol and distributed oblivious transfer protocol (DOTP). DOTP is the general OTP in the distributed setting. Private information retrieval (PIR) and symmetric private information retrieval (SPIR) problems are also analogous to those of the OTP. Due to its importance, the task of constructing efficient and secure OTP has attracted a lot interests. In this paper, a paradigm of OPT protocol and a practical fully-simulatable OTP protocol based on blind GDH (Gap Diffie-Hellman) signature are presented. The proposed schemes can achieve higher efficiency and better security than the popular Malkhi & Sella scheme. The salient property of short signature length of GDH signature scheme enables our proposals applicable to low-bandwidth communication environments.

Xinguo Li

Based on the RSA signature and (string) oblivious transfer, an enhanced oblivious transfer protocol is proposed which solves the access control problem for an oblivious transfer protocol. The protocol proposed has the property that only the receiver who has the signture issued by the central authority can open the message which he choose and that the sender can not decide whether the receiver has the signature or not. That is to say, the identity of the receiver can not be confirmed after the protocol. Under the decisional Diffie-Hellman assumption the proposed scheme has provable security.

Michael J. Fischer, Silvio M. Micali, Charles Rackoff