彌封式競拍系統之密碼協定

Abstract

網際網路的普及與便利促進了電子商務的蓬勃發展, 傳統上面對面的互動行為逐漸轉為電子式的交易程序, 由各個買家互相競價決定商品價格的拍賣系統即為一例。在本篇論文中, 我們提出另一種方法解決數值比大小的問題, 並將此概念應用到兩人比價與彌封式競拍系統中。經此提出的方法不需要可信任的第三者支援, 在效能方面, 兩人比價的協定僅需要兩回合溝通, 競拍系統則利用一個公開的電子佈告欄做為投標者之間的聯繫, 這需要二或三回合的互動, 我們的方法不會洩露投標者的標價又能有效地達到比價的目的。

The prevalence of Internet has promoted the development of E-commerce. Traditional face-to-face tradings are translated into electronic mechanisms: for instance, auctions. Sealed-bid auctions are a kind of auctions that bidders send their sealed bidding prices to the auctioneer and the auctioneer opens all bids to determine the winner and the winning bid. Many researchers are devoted to the study of secure and efficient sealed-bid auctions. In this thesis, a novel construction on the secure computation of the greater-than function is proposed. We apply this idea to the two-party private bidding and sealed-bid auction protocols. Our protocols require no trusted servers. In the private bidding protocol, it needs two rounds of communication between the bidders. In the auction protocol, a public bulletin board is used. It takes two or three rounds of communication between the bidders and the board. After the execution of our protocols, no bid information is revealed to any party.