标题：Practical Server-Aided k-out-of-n Oblivious Transfer Protocol
作者：Wei, Xiaochao; Zhao, Chuan; Jiang, Han; Xu, Qiuliang; Wang, Hao
作者机构：[Wei, Xiaochao; Zhao, Chuan; Jiang, Han; Xu, Qiuliang; Wang, Hao] Shandong Univ, Sch Comp Sci & Technol, Jinan, Peoples R China.
会议名称：11th International Conference on Green, Pervasive and Cloud Computing (GPC)
会议日期：MAY 06-08, 2016
来源：GREEN, PERVASIVE, AND CLOUD COMPUTING
关键词：k-out-of-n oblivious transfer; Server-aided; Decisional Diffie-Hellman; assumption; Cloud computing
摘要：Oblivious transfer (OT) is an important cryptographic primitive. In this paper, we propose a practical server-aided k-out-of-n oblivious transfer (OTnk) protocol based on the Decisional Diffie-Hellman (DDH) assumption. Our construction is the first one that is applicable in cloud computing environment. Unlike the original OT which only contains the receiver R and sender S, the server-aided OT setting also contains cloud servers who provide a vast amount of computational resources, therefore the sender and receiver can outsource the computational work to the cloud servers. In the proposed protocol, the receiver R sends only two group elements to the sender S, and S sends 2n group elements back to R. The computation cost of R and S is the most efficient comparing with other known schemes. In our protocol, the receiver R computes 2k + 3 modular exponentiations and the sender computes 2.5n modular exponentiations. The communication rounds of the protocol is three, including one extra round from the receiver R to the cloud servers. The choices of the receiver R is protected against the sender S and cloud servers, meanwhile, the input values of S which are not chosen are still secret to R.