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    一个单服务器辅助的高效n取k茫然传输协议

    An Efficient Single Server-Aided k-out-of-n Oblivious Transfer Protocol

    • 摘要: 茫然传输(oblivious transfer, OT)是一种用于隐藏数据接收者选择信息的密码学原语,作为构建高层多方密码协议的基本工具,在诸多具体问题中都有着重要应用.在k-out-of-n OT(OT\+k\-n)中,接收者能够以茫然的方式,在n个数据中有选择地取得其中的k个.通常OT\+k\-n的构造需要大量的群指数操作,对于计算能力受限的嵌入式设备而言依然是极大的负担.随着云计算的发展,可以利用云服务提供商的计算能力和高速专属网络来辅助复杂密码原语的实现.在此提出了一个高效单服务器辅助的n取k茫然传输协议,将主要群指数操作外包给云服务器来实现.该方案利用秘密分享等基础密码学原语构建,其安全性基于判定性Diffie-Hellamn(decisional Diffie-Hellamn, DDH)困难问题,在非合谋半诚实模型下可证明安全,同时可以保证云服务器的数据隐私性,给出该方案的具体描述及其详细的安全性证明.作为云环境下的一种基础密码学原语,所提出的云服务器辅助的茫然传输协议,在设计云辅助的通用安全计算协议及构建高效安全云服务应用软件等方面将起到重要作用.

       

      Abstract: Oblivious transfer (OT) is a cryptographic primitive used for choice information hiding for the receiver. As a basic tool for high-level multi-party cryptographic protocol construction, it plays an important role in numerous specific applications. In the k-out-of-n OT(OT\+k\-n), the receiver acquires k selections among the n choice in an oblivious manner. Generally, the construction of the OT\+k\-n involves lots of group exponential operations, which brings a heavy burden for embedded devices with limited computational capabilities. With the proliferation of cloud computing, it is feasible to implement complex cryptographic primitives with the support of powerful computing recourse and high-speed dedicated network provided by the cloud service provider (CSP). In this paper, we propose a service-assisted k-out-of-n OT protocol in single server architecture, which outsources the vast majority of exponentiation operations to the cloud. This scheme is constructed with secret sharing and other fundamental public-key primitives, and it achieves provable security on none-collusion semi-honest model under the decisional Diffie-Hellamn (DDH) hard problem; meanwhile it ensures data privacy against the cloud server. Besides, a detailed description of scheme construction and security proof is presented in the context. As a basic cryptographic primitive in cloud environment, the single server-added oblivious transfer protocol will play an important role in designs of general cloud-assisted multi-party computation protocol as well as developments of secure and efficient cloud service software.

       

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