Title: Visually Sealed and Digitally Signed Electronic Documents
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Visually Sealed and Digitally Signed Electronic Documents: Building on Asian Tradition by Yin-Miao (Vicky), Liu Bachelor of Business (Computing) - 1993 Thesis submitted in accordance with the regulations for Master of Information Technology (Research) Information Security Research Centre Faculty of Information Technology Queensland University of Technology December 2004 DECLARATION The work contained in this thesis has not been submitted for a degree or diploma at any higher education institution. To the best of my knowledge and belief, this thesis contains no material previously published or written by another person except where due reference is made. Signed: Dated : 01-12-2004 i Acknowledgements This study could not have been possible without those who assisted and guided me in various ways through the course of the study. I would like to express my deepest and most sincere appreciation to them. Firstly, I would like to thank my principal supervisor Professor William Caelli for his tremendous support, guidance and understanding in both my study and work. Professor Caelli plays such an active role in the international Information Security community. Yet he still makes himself available for the research meetings and always provides vibrant advice to assist overcoming many research challenges. I would like thank Dr. Eleanor Crosby for taking such interest in my research and providing invaluable advice and guidance throughout this research. I also thank my associate supervisor, Dr. Ernest Foo for his guidance to this study. While undertaking this research, I experienced overwhelming support from my dear friends and colleagues. I appreciate my friend, Mr. Ross Dunning, who is also actively engaged with his several work commitments; however, he is able to provide pertinent advice to my academic writing. Ms. Rachel Cobcroft at all times offers her professionalism and passion to my academic writing correction and improvement. Her assistance has been such an encouragement and support to this study. Special appreciation goes to Rachel. I wish to thank Ms. Jan Wilcox, Professor Caelli’s personal assistant. Jan is always ready to lend a helping hand to the administrative aspect of my study and work. Particularly, she is always able to arrange the research meetings with Professor Caelli’s occupied schedule. My thanks also extend to Professor Caelli’s former personal assistant, Ms. Anne Hamburger. I owe a tremendous debt of gratitude to my loving Australian Mother. Her love, encouragement and understanding have been such a vital strength throughout this journey. Without her support by my side I could not have carried out this research and working concurrently. Finally, I offer my thanksgiving to God for support and for giving me the strength and understanding when most needed. ii Keywords Seals, signatures, signets, Biblical seals, Western seals, Chinese seals, Japanese seals, digital signatures, seal certificates and digital certificates, visualised signing and verification, visualised digital signatures, visualised digital certificates, PKI. iii Research Paper The following paper has been published and presented based on the material in this thesis. Liu, V., Caelli, W., Foo, E., and Russell, S., “Visually Sealed and Digitally Signed Documents” Proceedings of the Twenty-Seventh Australian Computer Science Conference (ACSC 2004), Dunedin, New Zealand, January 18-22, 2004, Australian Computer Science Communications, Vol. 26, pp. 287-294 (ISBN 1-920682-05-8) iv Abstract E-commerce has developed through the use of digital signatures, employing various forms of Public Key Infrastructure (PKI) to ensure the secure usage of digital signatures. Digital signatures are designed to facilitate the functions of traditional seals and handwritten signatures for the purposes of authentication, data integrity, and non-repudiation within the e-commerce environment. Historically, the authenticity of documentation has always been verified by the application of a recognisable visual stimulus to the document; however, the current digital signature regime overlooks the importance of this analogous sense of visualisation. One of the primary problems with existing digital signatures is that a digital signature does not “feel” like, or resemble, a traditional seal to the human observer, as it does not have a personal, recognisable, or aesthetic sense of visualisation. Currently, digital signatures, such as the OpenPGP (Pretty Good Privacy) digital signature, are attached to the end of an electronic document as a stream of printable ASCII characters. (RFC2440) This appears to the average user as a long, incomprehensible string of random characters offering no sense of identity or ownership by simple visual inspection. Additionally, digital signatures change each time they are applied, in contrast to traditional seals that remain consistent personal identifiers associated with individual signatories. The goal of this research is to promote enhancements to existing digital signature schemes in order to bridge the cultural gap between traditional seals and digital signatures. Culturally friendly features integrated into the digital signature have the potential to increase user acceptability of global e-commerce. This research investigates traditional seal cultures within the context of modern digital signatures, identifying the need to develop a new, culturally friendly, visualised digital signature scheme. The principles behind digital signatures are reviewed and the essential roles and responsibilities of a PKI are addressed. A practical analysis of PKI implementation is also essential. Taiwan is v selected as the focus of this research since its heritage is deeply rooted in, and strongly adheres to the Chinese seal culture. The Taiwanese government is in the process of adapting the traditional seal certificate system to the electronic digital signature system. Therefore it is pertinent to review the PKI implementation and digital signatures applications in Taiwan in this study. The purpose of this research is to make the intangible digital signature virtually tangible; i.e., to incorporate visualisation into the current digital signature practice. This research defines new private extensions to the X.509 v3 certificate, recommending that conforming visualised digital signature applications should then be developed to generate and/or recognise visual digital certificates in support of the proposed visualised digital signature scheme. The processes of visualised digital signature creation and of verification through the application of the visualised digital certificate are then explained. This is accompanied by a model of system analysis for developers of conforming implementations of this specification. This allows developers the freedom to select appropriate developing tools. An analysis of this research evaluates the quality of integrity, security, interoperability, performance, and flexibility offered by this proposal. Future directions for furthering research development conclude this dissertation. vi Table of Contents Chapter 1: Research Overview __________________________________________1 1.1 Research Problem ______________________________________________1 1.2 Research Goal _________________________________________________3 1.3 Research Outcomes _____________________________________________4 1.4 Research Scope ________________________________________________4 1.5 Related Work __________________________________________________5 1.5.1 Digital Signatures and Cultural Issues ________________________________ 5 1.5.2 Digital Signing within Existing Trust-Based Environments _______________ 6 1.5.3 Visible RSA Public Keys for PKI_____________________________________ 8 1.6 Thesis Structure ________________________________________________9 1.7 Chapter Summary _____________________________________________ 11 Chapter 2: Traditional Seals, Handwritten Signatures and Digital Signatures ___13 2.1 Rationale_____________________________________________________13 2.2 Introduction __________________________________________________13 2.3 Introduction to Seals and Signatures ______________________________15 2.3.1 Signature Definitions _____________________________________________ 15 2.3.2 Seal, Signet, and Chop Definitions __________________________________ 16 2.3.3 Traditional and Digital Signatures and Seals __________________________ 18 2.4 Biblical Seal Applications _______________________________________21 2.5 Indus Valley Seals _____________________________________________25 2.6 Western Seals _________________________________________________25 2.6.1 Founding Western Civilisations_____________________________________ 25 2.6.2 Seal Classes _____________________________________________________ 27 2.6.3 Seal Matrices ____________________________________________________ 29 2.6.4 Seal Attachments_________________________________________________ 30 2.6.5 Seal Functions ___________________________________________________ 31 vii 2.6.6 Legality of Western Seals __________________________________________ 32 2.7 Chinese Seals _________________________________________________34 2.7.1 Origin of Chinese Seals____________________________________________ 34 2.7.2 Significance of Chinese Seals _______________________________________ 34 2.7.3 Seal Faces, Knobs and Inscriptions __________________________________ 34 2.7.4 Functions of Ancient Chinese Seals __________________________________ 37 2.7.5 Classes of Ancient Chinese Seals ____________________________________ 38 2.7.6 Sealing