值基於橢圓曲線密碼系統的代理簽章機制之研究 鍾玉芳、陳澤雄 ; 余心淳
E-mail: 9225033@mail.dyu.edu.tw
摘 要
網路通訊技術的發展日新月異，造就線上交易與通信愈形普遍化的情形，可以想見電子商務將是未來資訊社會中商業活動 的主流，因此也更加突顯資訊安全的重要性。在現行的網路安全研究領域上，公開金鑰密碼系統是接受度相當高的研究方 向之一，該密碼系統運作中最關鍵的一環又非數位簽章機制莫屬，由於數位簽章技術的成熟與否對數位認證系統而言，具 有決定性的指標意義，同時也是公開金鑰基礎建設研究中最重要的組成部分，其應用面之廣，也包含本論文的研究題目─
代理簽章。 代理簽章技術及特性得以解決一般數位簽章在應用上的盲點，是非常值得著力的研究。所謂代理簽章，指的是 具有權限的原始簽署者，以授權的方式委託代理人代為簽署文件，賦予文件合法的文件效力；授權後，代理簽署者再持授 權資訊產生一個有效的代理簽章，對文件進行簽署；至於接收方驗證時，除了驗證簽章的有效性，同時還必須驗證授權資 訊的合法性。所以當原始簽署者因故不克出席行使其簽章之權力與義務時，則可透過代理簽章機制授權所委託之代理者代 為決行，以避免因時間點之延誤所導致的損失，進而提升執行程序之效能。代理簽章的相關應用還包括可移動代理、自我 代理、電子現金、匿名投票系統等。 本論文的研究重點主要以安全性為經，執行效能為緯，透過對代理簽章研究系統化的 歸納，深入探討相關文獻應用之理論，提出兩個因應不同應用需要的代理簽章機制，其一是不具代理保護的多重代理簽章 機制，另一則為具代理保護的多重代理簽章機制，並且應用橢圓曲線密碼系統低運算量與短金鑰的特色，在滿足代理簽章 機制所需的安全特性之餘，同時也具備一定的實用性，適用於網際網路資源有限之特殊環境，發展網路資訊科技。
關鍵詞 : 密碼系統 ; 數位簽章 ; 代理簽章 ; 電子商務安全
目錄
目 錄 封面內頁 簽名頁 授權書 1... iii 授權書 2... iv 中文摘 要... v 英文摘要... vii 誌謝... ix 目 錄... x 圖目錄... xiii 表目錄... xiv Chapter 1 Introduction 01 1.1 Background and Motivation of the Research... 01 1.2 Application of Public-Key
Cryptosystem... 04 1.3 History of Proxy-Signature Research... 05 1.4 Main Axes of the Thesis... 08 1.4.1 Proxy-unprotected Proxy Signature... 08 1.4.2 Proxy-protected Proxy Signature... 09 1.5 Organization of the Thesis... 09 Chapter 2 Elliptic Curve Cryptography... 11 2.1 Introduction to Elliptic Curve
Cryptography... 11 2.2 Theories of an Elliptic Curve... 13 2.2.1 Definition of an Elliptic Curve... 13 2.2.2 Elliptic Curve Additive Operation... 14 2.2.3 Elliptic Curve Multiplicative Operation... 17 2.3 Elliptic Curve Discrete Logarithm Problem... 18 Chapter 3 Application of Proxy-unprotected Proxy Multisignature Scheme... 20 3.1 Background of Proxy-unprotected Proxy Multisignature Scheme... 20 3.2 Related Work of Proxy-unprotected Proxy Multisignature Scheme of Sun... 21 3.3 The Proposed Elliptic Curve Proxy-unprotected Proxy Multisignature Scheme... 23 3.3.1 Initialization Procedure of the Elliptic Curve Cryptosystem... 23 3.3.2 Procedures of Authorization, delegation, and
Verification... 25 Chapter 4 Application of Proxy-protected Proxy Multisignature Scheme... 28 4.1 Background of Proxy-protected Proxy Multisignature
Scheme... 28 4.2 Related Work of Proxy-protected Proxy Multisignature Scheme of Sun... 29 4.3 The Proposed Elliptic Curve Proxy-protected Proxy Multisignature
Scheme... 31 4.3.1 Initialization Procedure of the Elliptic Curve Cryptosystem... 31 4.3.2 Procedures of Authorization, delegation, and Verification... 31 Chapter 5 Analyses of Performance and Security Concerns. 35 5.1 Analyses of Performance... 35 5.2 Security Concerns... 41 5.2.1 Security Caused by Elliptic Curve Discrete Logarithm Problem... 41 5.2.2 Public Key Substitution
Attack... 42 5.2.3 Selection of the Elliptic Curve... 43 5.3 Discussions on Resultant Performance and Security...
44 Chapter 6 Conclusions... 46 6.1 Contribution of the Proposals... 46 6.2 Perspective of Proxy-Signature Research... 47 Reference s... 48
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