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M.Sc. (Computer Science) / Please refer to full text to view abstract

M.Sc. / The aim of this dissertation (referred to as thesis in the rest of the document) is to investigate the concept of Single Sign-on (SSO) in heterogeneous computing environments and to provide guidelines and reference frameworks for the selection and successful implementation of SSO solutions. In doing so. it also provides an overview of the basic types of SSO, Secure Single Sign-on (SSSO) solutions, enabling technologies, as well as products currently available. Chapter 1 introduces the sign-on problem, the purpose and organization of the thesis and terminology and abbreviations used. The crux of the sign-on problem is that users are required to sign on to multiple systems, developed at different times and based on different technologies, each with its own set of signon procedures and passwords. This inevitably leads to frustration, loss of productivity and weakened security. Users frequently resort to writing down passwords or using trivial password that can easily be guessed. In Chapter 2 the concepts of Single Sign-on and a special subset of SSO, Secure Single Sign-on are defined. Five types of SSO solutions are identified, namely: Synchronization, Scripting, Proxies and Trusted Hosts. Trusted Authentication Server and Hybrid solutions. Of the available types of solutions, only Trusted Authentication Server and Hybrid solutions can provide Secure Single Sign-on if properly implemented. The security services for SSSO are identified as authentication, authorization, integrity, confidentiality, non-repudiation, security management and cryptographic services. Additional SSSO concepts, as well as the vulnerabilities, obstacles and pitfalls to introducing SSO solutions are discussed. Chapter 3 provides an overview of the most important SSO enabling technologies. The following technologies are discussed: OSF DCE, SESAME, Kerberos, DSSA/SPX, TESS, NetSp, Secure Tokens, GSS-API and Public key Cryptography. Chapter 4 discusses the Open Software Foundation's (OSF) Distributed Computing Environment (DCE). OSF DCE is one of the two open standards for distributed processing which are having a major influence on the development of single sign-on solutions and forms the basis of many existing SSO products. DCE is not a SSO product. but consists of specifications and software. The goal of DCE is to turn a computer network into a single, coherent computing engine. It is considered to be one of the fundamental building blocks for SSO solutions in the future. In Chapter 5 SESAME is discussed in some detail as another major enabling technology for SSO. Secure European System for Applications in a Multi-vendor Environment (SESAME) is an architecture that implements a model for the provision of security services within open systems developed by the European Computer Manufacturers Association (ECMA). The architecture was developed and implemented on a trial basis, by Bull, ICL and Siemens-Nixdorf in an initiative supported by the European Commission. Chapter 6 presents a list of 49 commercial SSO products currently available, classified according to the type of SSO solution. A few representative products are discussed in more detail to give an indication what functionality a prospective buyer could expect. The 'Ideal Single Sign-on' solution is presented in Chapter 7. Detailed requirements are listed. These requirements are uniquely identified by a code and classified as essential or recommended functionality required. Chapter 8 assimilates the information in the previous chapters into a structured evaluation, selection and implementation plan for SSO solutions, consisting of nine separate phases. It also proposes a reference framework for the evaluation and selection process. Chapter 9 concludes the thesis. Findings and conclusions are summarized as to the importance and impact of Single Sign-on as well as the expected future directions to be expected. In addition, recommendations for the future implementation of SSO and SSSO solutions in heterogeneous computing environments are made.

M.Com. (Computer Science) / The area covered in this study is that of logical security models. A logical security model refers to the formal representation of a security policy which allows the subsequent movement of rights between subjects and objects in a system. The best way to illustrate the goal of this study, is with the following abstract from the submitted article, which originated from this study. 'The original protection graph rewriting grammar used to simulate the different operations of the Take/Grant model is reviewed. The productions of the PGR-grammar is then expanded, by adding a new context which is based on the different security classes found in the Bell Grid LaPadula model [14].' The first goal of this study was to take the Take/Grant security -model and expand it. This expansion included the concept of assigning a different security class to each subject and object in the model. This concept was derived from the Bell and LaPadula model as discussed in chapter 2 of this study. The next goal that was defined, was to expand the PGR-grammar of [28], so that it would also be able to simulate .the operations of this expanded Take/Grant model. The .PGR-grammar consisted of different permitting and forbidding node and edge contexts. This PGR-grammar was expanded by adding an additional context to the formal representation. This expansion is explained in detail in chapter 5 of this study. The third goal was to take the expansions, mentioned above, and implement them in a computer system. This computer system had to make use of an expert. system in order to reach certain conclusions. Each of the operations of the Take/Grant model must be evaluated, to determine whether that rule can be applied or not. The use of the expert system is explained in chapters 6 and 7 of this study. This study consists out of eight chapters in the following order. Chapter 2 starts of with an introduction of some of the most important logical security models. This chapter gives the reader background knowledge of the different models available, which is essential for the rest of the study. This chapter, however, does not discuss the Take/Grant model in detail. This is done in chapter 3 of the study. In this chapter the Take Grant model is discussed as a major input to this study. The Send Receive model is also discussed as a variation of the Take/Grant model. In the last section of the chapter a comparison is drawn between these two models. Chapter 4 formalizes the Take/Grant model. The protection graph rewriting grammar (PGR-grammar), which is used to simulate the different operations of the Take/Grant model, is introduced...

M.Com. (Computer Science) / Please refer to full text to view abstract

M.Sc. (Computer Science) / Computer security is a key component in any computer system. Traditionally computers were not connected to one another. This centralized configuration made the implementation of computer security a relatively easy task. The closed nature of the system limited the number of unknown factors that could cause security breaches. The users and their access rights were generally well defined and the system was protected from outside threats through simple, yet effective control measures. The evolution of network environments changed the computer environment and in effect also computer security. It became more difficult to implement protection measures because the nature of the environment changed from closed to open. New defenses had to be developed for security issues like unknown parameters, increased points of attack, unknown paths of information etc. Businesses and the general public today depend on network systems and no person can ignore these and other related security problems. The widespread publicity of attacks, and better customer awareness on security issues, created a need for new solutions for computer security. Security organisations, businesses and universities are addressing these problems through the development of security standards and security solutions.Today computer systems are becoming more "safe" through new products such as encryption and decryption algorithms, single-sign on password facilities, biometrics systems, smart cards, firewalls etc. Another important security consideration is Access Control. Access Control is responsible for controlling the actions of users to resources.

M.Sc. (Computer Science) / Please refer to full text to view abstract

published_or_final_version / abstract / Computer Science and Information Systems / Master / Master of Philosophy

by Yuen Ching Wah. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 61-[63]). / Abstract also in Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Why use cryptography? --- p.1 / Chapter 1.2 --- Why is authentication important ？ --- p.2 / Chapter 1.3 --- What is the relationship between authentication and digital sig- nature? --- p.3 / Chapter 1.4 --- Why is random number important? --- p.3 / Chapter 2 --- Background --- p.5 / Chapter 2.1 --- Cryptography --- p.5 / Chapter 2.1.1 --- Symmetric key cryptography --- p.5 / Chapter 2.1.2 --- Asymmetric key cryptography --- p.7 / Chapter 2.1.3 --- Authentication --- p.8 / Chapter 2.2 --- Elliptic curve cryptography --- p.9 / Chapter 2.2.1 --- Mathematical background for Elliptic curve cryptography --- p.10 / Chapter 2.3 --- Pseudorandom number generator --- p.12 / Chapter 2.3.1 --- Linear Congruential Generator --- p.13 / Chapter 2.3.2 --- Inversive Congruential Generator --- p.13 / Chapter 2.3.3 --- PN-sequence generator --- p.14 / Chapter 2.4 --- Digital Signature Scheme --- p.14 / Chapter 2.5 --- Babai's lattice vector algorithm --- p.16 / Chapter 2.5.1 --- First Algorithm: Rounding Off --- p.17 / Chapter 2.5.2 --- Second Algorithm: Nearest Plane --- p.17 / Chapter 3 --- Several Digital Signature Schemes --- p.18 / Chapter 3.1 --- DSA --- p.19 / Chapter 3.2 --- Nyberg-Rueppel Digital Signature --- p.21 / Chapter 3.3 --- EC.DSA --- p.23 / Chapter 3.4 --- EC-Nyberg-Rueppel Digital Signature Scheme --- p.26 / Chapter 4 --- Miscellaneous Digital Signature Schemes and their PRNG --- p.29 / Chapter 4.1 --- DSA with LCG --- p.30 / Chapter 4.2 --- DSA with PN-sequence --- p.33 / Chapter 4.2.1 --- Solution --- p.35 / Chapter 4.3 --- DSA with ICG --- p.39 / Chapter 4.3.1 --- Solution --- p.40 / Chapter 4.4 --- EC_DSA with PN-sequence --- p.43 / Chapter 4.4.1 --- Solution --- p.44 / Chapter 4.5 --- EC一DSA with LCG --- p.45 / Chapter 4.5.1 --- Solution --- p.46 / Chapter 4.6 --- EC-DSA with ICG --- p.46 / Chapter 4.6.1 --- Solution --- p.47 / Chapter 4.7 --- Nyberg-Rueppel Digital Signature with PN-sequence --- p.48 / Chapter 4.7.1 --- Solution --- p.49 / Chapter 4.8 --- Nyberg-Rueppel Digital Signature with LCG --- p.50 / Chapter 4.8.1 --- Solution --- p.50 / Chapter 4.9 --- Nyberg-Rueppel Digital Signature with ICG --- p.51 / Chapter 4.9.1 --- Solution --- p.52 / Chapter 4.10 --- EC- Nyberg-Rueppel Digital Signature with LCG --- p.53 / Chapter 4.10.1 --- Solution --- p.54 / Chapter 4.11 --- EC- Nyberg-Rueppel Digital Signature with PN-sequence --- p.55 / Chapter 4.11.1 --- Solution --- p.56 / Chapter 4.12 --- EC-Nyberg-Rueppel Digital Signature with ICG --- p.56 / Chapter 4.12.1 --- Solution --- p.57 / Chapter 5 --- Conclusion --- p.59 / Bibliography --- p.61

published_or_final_version / Computer Science and Information Systems / Master / Master of Philosophy