| The concept of an oblivious transfer was introduced by M.Rabin, and has since then proven to be a powerful tool in the design of cryptographic protocols and to be a key component in many applications of cryptography. It has become the basis for realizing a broad class of cryptographic protocols, such as bit commitment, zero-knowledge proof and secure multiparty computation. In this paper we propose a summary of oblivious transfer protocols so that the readers have a whole impression of them. The more important is that we have researched two problems of OT, one is the OT protocols'efficiency, and the other is the application. With regard to the OT protocols'efficiency, we let the sender compute beforehand and design a non-interactive version of the OT previously existed. So we have improved the OT protocols'effi-ciency. Especially, we propose a more efficient k-out-of-n oblivious transfer scheme than the scheme proposed by Cheng-Kang Chu and Wen-Guey Tzeng. We have a comparison of our and Chu and Tzeng's schemes and we prove our scheme is more efficient than theirs. With regard to the OT protocols'application, we propose a example of the OT protocols' application, that is a private transaction mechanism ofdigital productions based on OT_n~1 which is based on any secure public keysystem. This is a two-party private transaction mechanism while assures that the verders can't ascertain what products their customer buys. The prerequisite of this mechanism is that all productions have the same price. So we improve this mechanism and propose another private transaction mechanism of digital productionswhich is based on OT_n~m. Here, the OT_n~m is also based on public key system. We have solved the problem when all productions have different prices and our mechanism is more efficient than running several times of the prior mechanism based on OT_n~1 . Finally, we summarize our creative results and the continual research of OT which also includes its security, reduction and achievement. |
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