It is wildly used in Yao’s protocol, GMW construction, and preprocessing phase of SPDZ-like protocols.
Oblivious transfer (OT) is one of the most important primitives in secure computation. We believe our construction may be a building block in other applications as well. Besides, can be used to construct high-level protocols, such as private membership test (PMT) and private set intersection (PSI). Whatever the number of rounds OT to be executed and the length of messages in OT to be sent, our protocol realizes optimal complexity. In, the sender works on the fly and performs only symmetric operations locally. We give a standard security definition, and the proposed protocol is proven secure in the semihonest model. In this paper, we propose a generic outsourced OT extension protocol ( ) that outsources all the asymmetric operations of the sender to a semihonest server so as to adapt to specific scenarios above. While most earlier works discussed security model or communication and computation complexity of OT in general case, we focus on concrete application scenarios, especially where the sender in the OT protocol is a database with less computation and limited interaction capability. OT extension protocol reduces expensive asymmetric operations by running a small number of OT instances first and then cheap symmetric operations. Oblivious transfer (OT) is a cryptographic primitive originally used to transfer a collection of messages from the sender to the receiver in an oblivious manner.