一個適用於Ad-hoc網路環境下的分散式提名代理簽章機制

Abstract

在現代數位化的時代中，數位簽章常被利用於各種電子文件的簽署。而在過去，數位簽章通常都是要由簽章人自行來產生，如此一來也造成了許多的不便。因此，為了破除這種當簽章者不在便不能簽署文件的窘境，有學者提出了代理簽章的概念。如此一來，就算簽署者不在，亦可以指定一位代理人來幫他執行簽章的動作以產行有效的數位簽章。然而在相較於結構較為鬆散及節點流動性極大的Ad-hoc網路環境下，目前並沒有一個較為適合的代理簽章方式可以套用。因此，本篇論文便試著將各種現存的代理簽章方式截長補短，以Threshold Proxy Signature中的secret sharing方法來分散運算，此外，亦搭配El-Gamal的觀念來提高新方法的security，提出一個更符合Ad-hoc網路環境的分散式提名代理簽章方法，而在論文的最後面，我們會利用Manik Lal Das提出的幾點數位代理簽章安全性需求及Kaliski提出的方法來對新舊方法做分析評估，以證明新方法較具安全性及彈性

Digital signature which is usually used in many kinds of digital documents and only generated by the original signer in this digital age may result in several inconveniences. So, in order to solve the dilemma that digital signatures can’t be generated without the original signer, some scholars proposed a new scheme called Proxy Signature. By the showing up of Proxy signature scheme, the original signer could designate a proxy to perform the signing by generating valid digital signatures on behalf of the original signer when it is not there. However, there is no suitable scheme which could be applied to the Ad-hoc network environment due to its loose structure and unstable topology of mobile nodes. In order to find out a new scheme that could be used in Ad-hoc network environment, I tried to collect and analysis advantages and disadvantages of every related scheme, for example, I try to incorporate the secret sharing mechanism of Threshold Proxy Signature into my new mechanism, besides, I also benefit from using the concept of El-Gamal to improve the security to make a more suited distributed nominative proxy signature mechanism for Ad-hoc network. At last, we will show better security and flexibility the new mechanism has by Manik Lal Das’s basic proxy signature scheme security requirements and Kaliskis’ methodology to perform computing time analysis.