基于不经意传输的合同签订协议

A Protocol for Signing Contracts Based on Oblivious Transfer

在网络环境中解决合同签订问题需要保证信息交换的同时性 ,以前提出的协议都会给第 2个发送者部分计算特权 ,利用不经意传输协议则可以解决这个问题 在协议执行过程中 ,参与者将合同的签名位以及他对签名位的承诺不经意传输给对方 ,对方可以利用验证子协议证明该位的有效性 ,但是他却不能通过位交换次数的增加获取更多的完整签名的信息 ;在完成签名位的交换之后 ,参与者分别宣布承诺 ,并得到对方对合同的完整签名 ;在宣布承诺时 ,协议参与者已经获得全部的签名内容 ,要么是签名位 ,要么是对方对该位的承诺 ,因此参与者并不需要担心对方提前终止协议

If two parties want to sign a contract C over a communication network, they must “simultaneously” exchange their commitments to C Since simultaneous exchange is usually impossible in practice, protocols are needed to approximate simultaneity by exchange partial commitments in a piece by piece manner The party of secondly sending commitments may have a slight advantage; a “fair” protocol must keep this advantage within acceptable limits The protocol for signing a contract is improved based on the research result of secure multiparty computation In this protocol, the parties obliviously transfer the signed bit and the committed bit; the other parties can prove the validity of this bit based on the confirming sub protocol, but he can't gain more information about the whole signature by accumulating the signed bit or the committed bit After the parties exchange the whole signed information, they declare the commitment about the signature respectively, and gain the whole signature of the other party At this moment, the party doesn't care about the advance quit of the other party, because he has gained the whole signed information Finally, it is proved that this protocol is quit fairness