by Cheng Siu Lung. / "August 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

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

The topic of this thesis is black virus disinfection using mobile agents. The black virus is a faulty node that destroys any visiting agent without leaving a trace; moreover, once the black virus is triggered by an agent, it clones itself and spreads to neighbouring nodes. These viruses can only be destroyed if they move to nodes that have been occupied by agents. In this thesis, we consider the black virus disinfection problem in chordal rings. Initially, the system contains a single black virus that resides at an unknown location. We propose a solution that involves deploying a team of mobile agents to locate the original black virus and to prevent further damage once it has been triggered. Our protocol is divided into two phases: 1) searching the graph until the black virus is found and triggered and 2) sending agents to occupy the neighbouring nodes of the black virus in order to trigger and destroy all the black viruses at once. Our solutions are monotone, meaning that once a node has been explored it is protected from re-infection. In order to measure the efficiency of our protocol we consider the total number of agents required for disinfection, the overall number of black viruses and the number of moves required by the agents. We then analyze the cost of all our solutions, providing optimal bounds for some classes of chordal rings.

The topic of this thesis is black virus disinfection using mobile agents. The black virus is a faulty node that destroys any visiting agent without leaving a trace; moreover, once the black virus is triggered by an agent, it clones itself and spreads to neighbouring nodes. These viruses can only be destroyed if they move to nodes that have been occupied by agents. In this thesis, we consider the black virus disinfection problem in chordal rings. Initially, the system contains a single black virus that resides at an unknown location. We propose a solution that involves deploying a team of mobile agents to locate the original black virus and to prevent further damage once it has been triggered. Our protocol is divided into two phases: 1) searching the graph until the black virus is found and triggered and 2) sending agents to occupy the neighbouring nodes of the black virus in order to trigger and destroy all the black viruses at once. Our solutions are monotone, meaning that once a node has been explored it is protected from re-infection. In order to measure the efficiency of our protocol we consider the total number of agents required for disinfection, the overall number of black viruses and the number of moves required by the agents. We then analyze the cost of all our solutions, providing optimal bounds for some classes of chordal rings.

Mobile agent technology presents an attractive alternative to the client-server paradigm for several network and real-time applications. However, for most applications, the lack of a viable agent security model has limited the adoption of the agent paradigm. This thesis presents a security model for mobile agents based on a security infrastructure for Computational Grids, and specifically, on X.509 Proxy Certificates. Proxy Certificates serve as credentials for Grid applications, and their primary purpose is temporary delegation of authority. Exploiting the similarity between Grid applications and mobile agent applications, this thesis motivates the use of Proxy Certificates as credentials for mobile agents. A new extension for Proxy Certificates is proposed in order to make them suited to mobile agent applications, and mechanisms are presented for agent-to-host authentication, restriction of agent privileges, and secure delegation of authority during spawning of new agents. Finally, the implementation of the proposed security mechanisms as modules within a multi-lingual and modular agent infrastructure, the Distributed Agent Delivery System, is discussed.

With the growing popularity of e-commerce applications that use software agents, the protection of mobile agent data has become imperative. To that end, the performance of four methods that protect the data integrity of mobile agents is evaluated. The methods investigated include existing approaches known as the Partial Result Authentication Codes, Hash Chaining, and Set Authentication Code methods, and a technique of our own design, called the Modified Set Authentication Code method, which addresses the limitations of the Set Authentication Code method. The experiments were run using the DADS agent system (developed at the Network Research Laboratory at UNT), for which a Data Integrity Module was designed. The experimental results show that our Modified Set Authentication Code technique performed comparably to the Set Authentication Code method.

An increasingly promising and widespread topic of research in distributed computing is the mobile agent paradigm: code travelling and performing computations on remote hosts in an autonomous manner. One of the biggest challenges faced by this new paradigm is security. The issue of protecting sensitive code and data carried by a mobile agent against tampering from a malicious host is particularly hard but important. Based on secure multi-party computation, a recent research direction shows the feasibility of a software-only solution to this problem, which had been deemed impossible by some researchers previously. The best result prior to this dissertation is a single-agent protocol which requires the participation of a trusted third party. Our research employs multi-agent protocols to eliminate the trusted third party, resulting in a protocol with minimum trust assumptions. This dissertation presents one of the first formal definitions of secure mobile agent computation, in which the privacy and integrity of the agent code and data as well as the data provided by the host are all protected. We present secure protocols for mobile agent computation against static, semi-honest or malicious adversaries without relying on any third party or trusting any specific participant in the system. The security of our protocols is formally proven through standard proof technique and according to our formal definition of security. Our second result is a more practical agent protocol with strong security against most real-world host attacks. The security features are carefully analyzed, and the practicality is demonstrated through implementation and experimental study on a real-world mobile agent platform. All these protocols rely heavily on well-established cryptographic primitives, such as encrypted circuits, threshold decryption, and oblivious transfer. Our study of these tools yields new contributions to the general field of cryptography. Particularly, we correct a well-known construction of the encrypted circuit and give one of the first provably secure implementations of the encrypted circuit.

by Chan Pui Chung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves [56]-[61]). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- The Trends --- p.1 / Chapter 1.2 --- What this Thesis Contains --- p.3 / Chapter 2 --- Background --- p.5 / Chapter 2.1 --- Computer Security --- p.5 / Chapter 2.2 --- Anti-intrusion Techniques --- p.6 / Chapter 2.3 --- The Need for Intrusion Detection System --- p.7 / Chapter 2.4 --- Intrusion Detection System Categorization --- p.8 / Chapter 2.4.1 --- Network-based vs. Host-based --- p.8 / Chapter 2.4.2 --- Anomaly Detection vs. Misuse Detection --- p.10 / Chapter 2.4.3 --- Centralized vs. Distributed --- p.11 / Chapter 2.5 --- Agent-based IDS --- p.12 / Chapter 2.6 --- Mobile agent-based IDS --- p.12 / Chapter 3 --- Survey on Intrusion Step --- p.14 / Chapter 3.1 --- Introduction --- p.14 / Chapter 3.2 --- Getting information before break in --- p.14 / Chapter 3.2.1 --- Port scanning --- p.14 / Chapter 3.2.2 --- Sniffing --- p.16 / Chapter 3.2.3 --- Fingerprinting --- p.17 / Chapter 3.3 --- Intrusion method --- p.17 / Chapter 3.3.1 --- DOS and DDOS --- p.17 / Chapter 3.3.2 --- Password cracking --- p.18 / Chapter 3.3.3 --- Buffer overflows --- p.19 / Chapter 3.3.4 --- Race Condition --- p.20 / Chapter 3.3.5 --- Session Hijacking --- p.20 / Chapter 3.3.6 --- Computer Virus --- p.21 / Chapter 3.3.7 --- Worms --- p.21 / Chapter 3.3.8 --- Trojan Horse --- p.22 / Chapter 3.3.9 --- Social Engineering --- p.22 / Chapter 3.3.10 --- Physical Attack --- p.23 / Chapter 3.4 --- After intrusion --- p.23 / Chapter 3.4.1 --- Covering Tracks --- p.23 / Chapter 3.4.2 --- Back-doors --- p.23 / Chapter 3.4.3 --- Rootkits --- p.23 / Chapter 3.5 --- Conclusion --- p.24 / Chapter 4 --- A Survey on Intrusion Detection System --- p.25 / Chapter 4.1 --- Introduction --- p.25 / Chapter 4.2 --- Information Source --- p.25 / Chapter 4.2.1 --- Host-based Source --- p.25 / Chapter 4.2.2 --- Network-based Source --- p.26 / Chapter 4.2.3 --- Out-of-band Source --- p.27 / Chapter 4.2.4 --- Data Fusion from multiple sources --- p.27 / Chapter 4.3 --- Detection Technology --- p.28 / Chapter 4.3.1 --- Intrusion signature --- p.28 / Chapter 4.3.2 --- Threshold Detection --- p.31 / Chapter 4.3.3 --- Statistical Analysis --- p.31 / Chapter 4.3.4 --- Neural Network --- p.32 / Chapter 4.3.5 --- Artificial Immune System --- p.33 / Chapter 4.3.6 --- Data Mining --- p.33 / Chapter 4.3.7 --- Traffic Analysis --- p.34 / Chapter 4.4 --- False Alarm Rate --- p.35 / Chapter 4.5 --- Response --- p.35 / Chapter 4.6 --- Difficulties in IDS --- p.36 / Chapter 4.6.1 --- Base Rate Fallacy --- p.36 / Chapter 4.6.2 --- Denial of Service Attack against IDS --- p.37 / Chapter 4.6.3 --- Insertion and Evasion attack against the Network-Based IDS . --- p.37 / Chapter 4.7 --- Conclusion --- p.38 / Chapter 5 --- Preemptive Distributed Intrusion Detection using Mobile Agents --- p.39 / Chapter 5.1 --- Introduction --- p.39 / Chapter 5.2 --- Architecture Design --- p.40 / Chapter 5.2.1 --- Overview --- p.40 / Chapter 5.2.2 --- Agents involved --- p.40 / Chapter 5.2.3 --- Clustering --- p.42 / Chapter 5.3 --- How it works --- p.44 / Chapter 5.3.1 --- Pseudo codes of operations --- p.48 / Chapter 5.4 --- Advantages --- p.49 / Chapter 5.5 --- Drawbacks & Possible Solutions --- p.49 / Chapter 5.6 --- Other Possible Mode of Operation --- p.50 / Chapter 5.7 --- Conclusion --- p.51 / Chapter 6 --- Conclusion --- p.52 / A Paper Derived from this Thesis --- p.54 / Bibliography --- p.55

Yu Chiu-Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 93-96). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.ii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Advantages of mobile agents --- p.2 / Chapter 1.2 --- Security --- p.3 / Chapter 1.3 --- Contributions --- p.3 / Chapter 1.4 --- Structure --- p.4 / Chapter 2 --- The Problem of Execution Tampering Attack --- p.5 / Chapter 2.1 --- Mobile agent execution model --- p.5 / Chapter 2.2 --- Tampering attack from malicious hosts --- p.5 / Chapter 2.3 --- Open network environment --- p.6 / Chapter 2.4 --- Conclusion --- p.6 / Chapter 3 --- Existing Approaches to Solve the Execution Tampering Prob- lem --- p.8 / Chapter 3.1 --- Introduction --- p.8 / Chapter 3.2 --- Trusted execution environment --- p.9 / Chapter 3.2.1 --- Closed system --- p.9 / Chapter 3.2.2 --- Trusted hardware --- p.9 / Chapter 3.3 --- Tamper-detection --- p.11 / Chapter 3.3.1 --- Execution tracing --- p.11 / Chapter 3.4 --- Tamper-prevention --- p.12 / Chapter 3.4.1 --- Blackbox security --- p.12 / Chapter 3.4.2 --- Time limited blackbox --- p.13 / Chapter 3.4.3 --- Agent mess-up --- p.15 / Chapter 3.4.4 --- Addition of noisy code --- p.15 / Chapter 3.4.5 --- Co-operating agents --- p.16 / Chapter 3.5 --- Conclusion --- p.17 / Chapter 4 --- Tamper-Detection Mechanism of Our Protocol --- p.18 / Chapter 4.1 --- Introduction --- p.18 / Chapter 4.2 --- Execution tracing --- p.18 / Chapter 4.3 --- Code obfuscation --- p.21 / Chapter 4.3.1 --- Resilience of obfuscating transformation --- p.22 / Chapter 4.4 --- Execution tracing with obfuscated program --- p.23 / Chapter 4.5 --- Conclusion --- p.27 / Chapter 5 --- A Flexible Tamper-Detection Protocol by Using Cooperating Agents --- p.28 / Chapter 5.1 --- Introduction --- p.28 / Chapter 5.1.1 --- Agent model --- p.29 / Chapter 5.1.2 --- Execution model --- p.30 / Chapter 5.1.3 --- System model --- p.30 / Chapter 5.1.4 --- Failure model --- p.30 / Chapter 5.2 --- The tamper-detection protocol --- p.30 / Chapter 5.3 --- Fault-tolerance policy --- p.38 / Chapter 5.4 --- Costs of the protocol --- p.38 / Chapter 5.5 --- Discussion --- p.40 / Chapter 5.6 --- Conclusion --- p.42 / Chapter 6 --- Verification of the Protocol by BAN Logic --- p.43 / Chapter 6.1 --- Introduction --- p.43 / Chapter 6.2 --- Modifications to BAN logic --- p.44 / Chapter 6.3 --- Term definitions --- p.45 / Chapter 6.4 --- Modeling of our tamper-detection protocol --- p.46 / Chapter 6.5 --- Goals --- p.47 / Chapter 6.6 --- Sub-goals --- p.48 / Chapter 6.7 --- Assumptions --- p.48 / Chapter 6.8 --- Verification --- p.49 / Chapter 6.9 --- Conclusion --- p.53 / Chapter 7 --- Experimental Results Related to the Protocol --- p.54 / Chapter 7.1 --- Introduction --- p.54 / Chapter 7.2 --- Experiment environment --- p.54 / Chapter 7.3 --- Experiment procedures --- p.55 / Chapter 7.4 --- Experiment implementation --- p.56 / Chapter 7.5 --- Experimental results --- p.61 / Chapter 7.6 --- Conclusion --- p.65 / Chapter 8 --- Extension to Solve the ´حFake Honest Host´ح Problem --- p.68 / Chapter 8.1 --- Introduction --- p.68 / Chapter 8.2 --- "The method to solve the ""fake honest host"" problem" --- p.69 / Chapter 8.2.1 --- Basic idea --- p.69 / Chapter 8.2.2 --- Description of the method --- p.69 / Chapter 8.3 --- Conclusion --- p.71 / Chapter 9 --- Performance Improvement by Program Slicing --- p.73 / Chapter 9.1 --- Introduction --- p.73 / Chapter 9.2 --- Deployment of program slicing --- p.73 / Chapter 9.3 --- Conclusion --- p.75 / Chapter 10 --- Increase Scalability by Supporting Multiple Mobile Agents --- p.76 / Chapter 10.1 --- Introduction --- p.76 / Chapter 10.2 --- Supporting multiple mobile agents --- p.76 / Chapter 10.3 --- Conclusion --- p.78 / Chapter 11 --- Deployment of Trust Relationship in the Protocol --- p.79 / Chapter 11.1 --- Introduction --- p.79 / Chapter 11.2 --- Deployment of trust relationship --- p.79 / Chapter 11.3 --- Conclusion --- p.82 / Chapter 12 --- Conclusions and Future Work --- p.83 / A Data of Experimental Results --- p.86 / Publication --- p.92 / Bibliography --- p.93

Este texto apresenta nosso projeto de implementação de um arcabouço de suporte a agentes móveis dentro de um ambiente de grade denominado InteGrade. Nosso arcabouço - MobiGrid - foi criado de forma a permitir que aplicações seqüenciais longas possam ser executadas em uma rede de estações de trabalho pessoais. Os agentes móveis são utilizados para encapsular essas aplicações com longo tempo de processamento. O encapsulamento de uma aplicação com longo tempo de processamento dentro de um agente móvel é o que denominamos como tarefa. Sendo assim, as tarefas podem migrar sempre que a máquina é requisitada por seu usuário local, já que são providas com capacidade de migração automática. Nosso arcabouço também fornece ao usuário um gerente que rastreia as tarefas por ele submetidas. Baseados no ambiente de execução de tarefas descrito, criamos um modelo matemático para efetuarmos simulações de como se comportariam muitas tarefas submetidas a uma grade com grande quantidade de estações de trabalho. Neste trabalho apresentamos também esse modelo, bem como os resultados das simulações nele baseadas. / This text presents a project which focuses on the implementation of a framework for mobile agents support within a grid environment project, namely InteGrade. Our framework - MobiGrid - was created in such a way that time consuming sequential applications can be executed on a network of personal workstations. The encapsulation of a long processing application by a mobile agent is what we call task. Hence, the tasks can migrate whenever the local machine is requested by its local user, since they are provided with automatic migration capabilities. Our framework also provides the user with a manager that keeps track of the submitted agents. Based on the execution environment described above, we have created a mathematical model which allows us to simulate how a great quantity of tasks submitted to a grid with many workstations would behave. In this text, we also present our model, as well as the results of our simulations.