Trust Management Survey
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paper_title: Human Experiments in Trust Dynamics

paper_content:

In the literature, the validity of theories or models for trust is usually based on intuition and common sense. Theories and models are not often verified experimentally. The research reported here contributes results of experiments on the dynamics of trust over time depending on positive or negative experiences. In previous research a number of dynamic properties for such trust dynamics were identified, but not verified empirically. As a continuation of this work, now these properties have been verified in an experimental setting. The outcomes of the experiment (involving a substantial number of 238 subjects) are discussed and related to the previously formulated dynamic properties.
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paper_title: A computational model of trust and reputation

paper_content:

Despite their many advantages, e-businesses lag behind brick and mortar businesses in several fundamental respects. This paper concerns one of these: relationships based on trust and reputation. Recent studies on simple reputation systems for e-Businesses such as eBay have pointed to the importance of such rating systems for deterring moral hazard and encouraging trusting interactions. However, despite numerous studies on trust and reputation systems, few have taken studies across disciplines to provide an integrated account of these concepts and their relationships. This paper first surveys existing literatures on trust, reputation and a related concept: reciprocity. Based on sociological and biological understandings of these concepts, a computational model is proposed. This model can be implemented in a real system to consistently calculate agents' trust and reputation scores.
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paper_title: Managing Internet-Mediated Community Trust Relations

paper_content:

This paper advances a framework for analysing and managing community trust relations. The framework is based upon an analysis of the evidence for different forms of trust in community relations and of the experiential dimensions of community relations that promote trust levels. It features a community trust cycle, a trust compact and an experience management matrix which collectively support managers in addressing the relational dynamics of community trust relations. We show that this framework can be used to analyse relations that are mediated by ICT and that the framework supports the identification of opportunities to better promote ICT-mediated trust development and promulgation.
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paper_title: Towards Dynamic Security Perimeters for Virtual Collaborative Networks

paper_content:

Rapid technological advancements capitalising on the convergence of information (middleware) and communication (network) technologies now enable open application-to-application communication and bring about the prospect of ad hoc integration of systems across organisational boundaries to support collaborations that may last for a single transaction or evolve dynamically over a longer period. Architectures for managing networks of collaborating peers in such environments face new security and trust management challenges. In this paper we will introduce the basic elements of such an architecture emphasising trust establishment, secure collaboration, distributed monitoring and performance assessment issues.
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paper_title: Engineering Trust Based Collaborations in a Global Computing Environment

paper_content:

Trust management seems a promising approach for dealing with security concerns in collaborative applications in a global computing environment. However, the characteristics of this environment require a move from reliable identification to mechanisms for the recognition of entities. Furthermore, they require explicit reasoning about the risks of interactions, and a notion of uncertainty in the underlying trust model. From our experience of engineering collaborative applications in such an environment, we found that the relationship between trust and risk is a fundamental issue. In this paper, as an initial step towards an engineering approach for the development of trust based collaborative applications, we focus on the relationship between trust and risk, and explore alternative views of this relationship. We also exemplify how particular views can be exploited in two particular application scenarios. This paper builds upon our previous work in developing a general model for trust based collaborations.
---
paper_title: A computational model of trust and reputation

paper_content:

Despite their many advantages, e-businesses lag behind brick and mortar businesses in several fundamental respects. This paper concerns one of these: relationships based on trust and reputation. Recent studies on simple reputation systems for e-Businesses such as eBay have pointed to the importance of such rating systems for deterring moral hazard and encouraging trusting interactions. However, despite numerous studies on trust and reputation systems, few have taken studies across disciplines to provide an integrated account of these concepts and their relationships. This paper first surveys existing literatures on trust, reputation and a related concept: reciprocity. Based on sociological and biological understandings of these concepts, a computational model is proposed. This model can be implemented in a real system to consistently calculate agents' trust and reputation scores.
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paper_title: Hardware security appliances for trust

paper_content:

This paper looks at the trust relationships that exist within an outsourcing scenario finding that whilst some of the trust relationships are clear other implicit trust relationships need exposing. These implicit trust relationships are often a result of information supplied for the main explicit task for which an entity is being trusted. The use of hardware security appliance based services is proposed allowing trust to be dissipated over multiple parties whilst retaining efficient execution. Such an approach helps mitigate these implicit trust relationships by increasing the control and transparency given to the trustor.
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paper_title: Analysing the Relationship between Risk and Trust

paper_content:

Among the various human factors impinging upon making a decision in an uncertain environment, risk and trust are surely crucial ones. Several models for trust have been proposed in the literature but few explicitly take risk into account. This paper analyses the relationship between the two concepts by first looking at how a decision is made to enter into a transaction based on the risk information. We then draw a model of the invested fraction of the capital function of a decision surface. We finally define a model of trust composed of a reliability trust as the probability of transaction success and a decision trust derived from the decision surface.
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paper_title: Trust Development and Management in Virtual Communities

paper_content:

The web is increasingly used as a platform and an enabler for the existence of virtual communities. However, there is evidence that the growth and adoption of these communities is being held back by many barriers- including that of trust development and management. This paper discusses the potential benefits and barriers to the introduction of trust development and management in virtual communities. Based on the analysis of the barriers and benefits of trust development and management, mechanisms for supporting its development and management is proposed and presented. Ideas for further research are presented and discussed. The paper is based on ongoing research and is part of a research bid towards the introduction of a trust development and management framework to support the creation of trusted virtual communities.
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paper_title: Modeling Controls for Dynamic Value Exchanges in Virtual Organizations

paper_content:

The e 3 -value modeling tool was developed for the design of a value proposition for virtual organizations. However, it is less suitable for designing the control structure of the virtual organization. We show how e 3 -value can be extended using legal concepts such as ownership, possession, usufruct and license. We also introduce value object transfer diagrams that show the transfers of value objects graphically and that can be used for elicitation of the required control mechanisms in order for the virtual organization to function properly and with a level of risk that is acceptable to all parties in the virtual organization.
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paper_title: Designing and Evaluating E-Business Models

paper_content:

This article presents an e-business modeling approach that combines the rigorous approach of IT systems analysis with an economic value perspective from business sciences.
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paper_title: Trust Propagation in Small Worlds

paper_content:

The possibility of a massive, networked infrastructure of diverse entities partaking in collaborative applications with each other increases more and more with the proliferation of mobile devices and the development of ad hoc networking technologies. In this context, traditional security measures do not scale well. We aim to develop trust-based security mechanisms using small world concepts to optimise formation and propagation of trust amongst entities in these vast networks. In this regard, we surmise that in a very large mobile ad hoc network, trust, risk, and recommendations can be propagated through relatively short paths connecting entities. Our work describes the design of trust-formation and risk-assessment systems, as well as that of an entity recognition scheme, within the context of the small world network topology.
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paper_title: KAoS: A Policy and Domain Services Framework for Grid Computing and Semantic Web Services

paper_content:

In this article we introduce KAoS, a policy and domain services framework based on W3C’s OWL ontology language. KAoS was developed in response to the challenges presented by emerging semantic application requirements for infrastructure, especially in the area of security and trust management. The KAoS architecture, ontologies, policy representation, management and disclosure mechanisms are described. KAoS enables the specification and enforcement of both authorization and obligation policies. The use of ontologies as a source of policy vocabulary enables its extensibility. KAoS has been adapted for use in several applications and deployment platforms. We briefly describe its integration with the Globus Grid Computing environment.
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paper_title: Towards Dynamic Security Perimeters for Virtual Collaborative Networks

paper_content:

Rapid technological advancements capitalising on the convergence of information (middleware) and communication (network) technologies now enable open application-to-application communication and bring about the prospect of ad hoc integration of systems across organisational boundaries to support collaborations that may last for a single transaction or evolve dynamically over a longer period. Architectures for managing networks of collaborating peers in such environments face new security and trust management challenges. In this paper we will introduce the basic elements of such an architecture emphasising trust establishment, secure collaboration, distributed monitoring and performance assessment issues.
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paper_title: Decentralized trust management

paper_content:

We identify the trust management problem as a distinct and important component of security in network services. Aspects of the trust management problem include formulating security policies and security credentials, determining whether particular sets of credentials satisfy the relevant policies, and deferring trust to third parties. Existing systems that support security in networked applications, including X.509 and PGP, address only narrow subsets of the overall trust management problem and often do so in a manner that is appropriate to only one application. This paper presents a comprehensive approach to trust management, based on a simple language for specifying trusted actions and trust relationships. It also describes a prototype implementation of a new trust management system, called PolicyMaker, that will facilitate the development of security features in a wide range of network services.
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paper_title: Engineering Trust Based Collaborations in a Global Computing Environment

paper_content:

Trust management seems a promising approach for dealing with security concerns in collaborative applications in a global computing environment. However, the characteristics of this environment require a move from reliable identification to mechanisms for the recognition of entities. Furthermore, they require explicit reasoning about the risks of interactions, and a notion of uncertainty in the underlying trust model. From our experience of engineering collaborative applications in such an environment, we found that the relationship between trust and risk is a fundamental issue. In this paper, as an initial step towards an engineering approach for the development of trust based collaborative applications, we focus on the relationship between trust and risk, and explore alternative views of this relationship. We also exemplify how particular views can be exploited in two particular application scenarios. This paper builds upon our previous work in developing a general model for trust based collaborations.
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paper_title: Simulating the Effect of Reputation Systems on E-markets

paper_content:

Studies show that reputation systems have the potential to improve market quality. In this paper we report the results of simulating a market of trading agents that uses the beta reputation system for collecting feedback and computing agents' reputations. The simulation confirms the hypothesis that the presence of the reputation system improves the quality of the market. Among other things it also shows that a market with limited duration rather than infinite longevity of transaction feedback provides the best conditions under which agents can adapt to each others change in behaviour.
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paper_title: Automated trust negotiation

paper_content:

Distributed software subjects face the problem of determining one another's trustworthiness. The problem considered is managing the exchange of credentials between strangers for the purpose of property-based authentication and authorization when credentials are sensitive. An architecture for trust negotiation between client and server is presented. The notion of a trust negotiation strategy is introduced and examined with respect to an abstract model of trust negotiation. Two strategies with very different properties are defined and analyzed. A language of credential expressions is presented, with two example negotiations illustrating the two negotiation strategies. Ongoing work on policies governing credential disclosure and trust negotiation is summarized.
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paper_title: Revocation in the Privilege Calculus

paper_content:

We have previously presented a framework for updating privileges and creating management structures by means of authority certificates. These are used both to create access-level permissions and to delegate authority to other agents. In this paper we extend the framework to support a richer set of revocation schemes. As in the original, we present an associated calculus of privileges, encoded as a logic program, for reasoning about certificates, revocations, and the privileges they create and destroy. The discussion of revocation schemes follows an existing classification in the literature based on three separate ::: dimensions: resilience, propagation, and dominance. The first does not apply to this framework. The second is specified straightforwardly. The third can be encoded but raises a number offurther questions for future investigation.
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paper_title: Server based application level authorisation for Rotor

paper_content:

Delegent is an authorisation server developed to provide a single centralised policy repository for multiple applications with support for decentralised administration by means of delegation. The author investigates how to integrate Delegent with the Rotor implementation of the .NET framework and compare the features of Delegent with those of the existing application level authorisation models of .NET. He concludes that Delegent offers help for application developers and a decentralised administration model, which are not available in standard .NET, and that the .NET model is well suited to be extended to use an authorisation server.
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paper_title: Specifying and Analysing Trust for Internet Applications

paper_content:

The Internet is now being used for commercial, social and educational interactions, which previously relied on direct face-to-face contact in order to establish trust relationships. Thus, there is a need to be able to establish and evaluate trust relationships relying only on electronic interactions over the Internet. A trust framework for Internet applications should incorporate concepts such as experience, reputation and trusting propensity in order to specify and evaluate trust. SULTAN (Simple Universal Logic-oriented Trust Analysis Notation) is an abstract, logic-oriented notation designed to facilitate the specification and analysis of trust relationships. SULTAN seeks to address all the above issues, although this paper focuses on our initial work on trust specification and analysis.
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paper_title: The Ponder Policy Specification Language

paper_content:

The Ponder language provides a common means of specifying security policies that map onto various access control implementation mechanisms for firewalls, operating systems, databases and Java. It supports obligation policies that are event triggered condition-action rules for policy based management of networks and distributed systems. Ponder can also be used for security management activities such as registration of users or logging and auditing events for dealing with access to critical resources or security violations. Key concepts of the language include roles to group policies relating to a position in an organisation, relationships to define interactions between roles and management structures to define a configuration of roles and relationships pertaining to an organisational unit such as a department. These reusable composite policy specifications cater for the complexity of large enterprise information systems. Ponder is declarative, strongly-typed and object-oriented which makes the language flexible, extensible and adaptable to a wide range of management requirements.
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paper_title: Analysing the Relationship between Risk and Trust

paper_content:

Among the various human factors impinging upon making a decision in an uncertain environment, risk and trust are surely crucial ones. Several models for trust have been proposed in the literature but few explicitly take risk into account. This paper analyses the relationship between the two concepts by first looking at how a decision is made to enter into a transaction based on the risk information. We then draw a model of the invested fraction of the capital function of a decision surface. We finally define a model of trust composed of a reliability trust as the probability of transaction success and a decision trust derived from the decision surface.
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paper_title: Challenges for trust, fraud and deception research in multi-agent systems

paper_content:

Discussions at the 5th Workshop on Deception, Fraud and Trust in Agent Societies held at the 1st International Joint Conference on Autonomous Agents and Multi-Agent Systems (AAMAS 2002) centered around many important research issues1. This paper attempts to challenge researchers in the community toward future work concerning three issues inspired by the workshop's roundtable discussion: (1) distinguishing elements of an agent's behavior that influence its trustworthiness, (2) building reputation-based trust models without relying on interaction, and (3) benchmarking trust modeling algorithms. Arguments justifying the validity of each problem are presented, and benefits from their solutions are enumerated.
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paper_title: A policy language for a pervasive computing environment

paper_content:

We describe a policy language designed for pervasive computing applications that is based on deontic concepts and grounded in a semantic language. The pervasive computing environments under consideration are those in which people and devices are mobile and use various wireless networking technologies to discover and access services and devices in their vicinity. Such pervasive environments lend themselves to policy-based security due to their extremely dynamic nature. Using policies allows the security functionality to be modified without changing the implementation of the entities involved. However, along with being extremely dynamic, these environments also tend to span several domains and be made up of entities of varied capabilities. A policy language for environments of this sort needs to be very expressive but lightweight and easily extensible. We demonstrate the feasibility of our policy language in pervasive environments through a prototype used as part of a secure pervasive system.
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paper_title: Supporting trust in virtual communities

paper_content:

At any given time, the stability of a community depends on the right balance of trust and distrust. Furthermore, we face information overload, increased uncertainty and risk taking as a prominent feature of modern living. As members of society, we cope with these complexities and uncertainties by relying trust, which is the basis of all social interactions. Although a small number of trust models have been proposed for the virtual medium, we find that they are largely impractical and artificial. In this paper we provide and discuss a trust model that is grounded in real-world social trust characteristics, and based on a reputation mechanism, or word-of-mouth. Our proposed model allows agents to decide which other agents' opinions they trust more and allows agents to progressively tune their understanding of another agent's subjective recommendations.
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paper_title: Patterns of trust and policy

paper_content:

This paper proposes a new paradigm of trust and policy that provides a unified treatment of organizational and data system policies. Policy is the programming language of organizations and just like any other language must be formally specified or specifiable. This paper attempts to demonstrate that it is specifiable. Trust is a major component of policy. Trust is presented as a function of specific elements - identity, reputation, capability, stake and benefit. These elements are defined and presented in the form of a trust equation. The points at which trust enters into the formal definition of policy are identified. The trust equation provides a useful way do &scribe trust in general that is not circular (unlike many previous definitions). The resulting constructs can be st&iently nontechnical that both systems people and those without a technical background can understand them The availability of a common language to guide analysis of policy requirements, policy formulation and policy execution may provide a way for organizations to break out of a recurring cycle of policy failures.
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paper_title: Using trust for secure collaboration in uncertain environments

paper_content:

The SECURE project investigates the design of security mechanisms for pervasive computing based on trust. It addresses how entities in unfamiliar pervasive computing environments can overcome initial suspicion to provide secure collaboration.
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paper_title: Decentralized trust management

paper_content:

We identify the trust management problem as a distinct and important component of security in network services. Aspects of the trust management problem include formulating security policies and security credentials, determining whether particular sets of credentials satisfy the relevant policies, and deferring trust to third parties. Existing systems that support security in networked applications, including X.509 and PGP, address only narrow subsets of the overall trust management problem and often do so in a manner that is appropriate to only one application. This paper presents a comprehensive approach to trust management, based on a simple language for specifying trusted actions and trust relationships. It also describes a prototype implementation of a new trust management system, called PolicyMaker, that will facilitate the development of security features in a wide range of network services.
---
paper_title: A computational model of trust and reputation

paper_content:

Despite their many advantages, e-businesses lag behind brick and mortar businesses in several fundamental respects. This paper concerns one of these: relationships based on trust and reputation. Recent studies on simple reputation systems for e-Businesses such as eBay have pointed to the importance of such rating systems for deterring moral hazard and encouraging trusting interactions. However, despite numerous studies on trust and reputation systems, few have taken studies across disciplines to provide an integrated account of these concepts and their relationships. This paper first surveys existing literatures on trust, reputation and a related concept: reciprocity. Based on sociological and biological understandings of these concepts, a computational model is proposed. This model can be implemented in a real system to consistently calculate agents' trust and reputation scores.
---
paper_title: Automated trust negotiation

paper_content:

Distributed software subjects face the problem of determining one another's trustworthiness. The problem considered is managing the exchange of credentials between strangers for the purpose of property-based authentication and authorization when credentials are sensitive. An architecture for trust negotiation between client and server is presented. The notion of a trust negotiation strategy is introduced and examined with respect to an abstract model of trust negotiation. Two strategies with very different properties are defined and analyzed. A language of credential expressions is presented, with two example negotiations illustrating the two negotiation strategies. Ongoing work on policies governing credential disclosure and trust negotiation is summarized.
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paper_title: Reasoning About Trust: A Formal Logical Framework

paper_content:

There is no consensus about the definition of the concept of trust. In this paper formal definitions of different kinds of trust are given in the framework of modal logic. This framework also allows to define a logic for deriving consequences from a set of assumptions about trust.Trust is defined as a mental attitude of an agent with respect to some property held by another agent. These properties are systematically analysed and we propose 6 epistemic properties, 4 deontic properties and 1 dynamic property.
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paper_title: Specifying and Analysing Trust for Internet Applications

paper_content:

The Internet is now being used for commercial, social and educational interactions, which previously relied on direct face-to-face contact in order to establish trust relationships. Thus, there is a need to be able to establish and evaluate trust relationships relying only on electronic interactions over the Internet. A trust framework for Internet applications should incorporate concepts such as experience, reputation and trusting propensity in order to specify and evaluate trust. SULTAN (Simple Universal Logic-oriented Trust Analysis Notation) is an abstract, logic-oriented notation designed to facilitate the specification and analysis of trust relationships. SULTAN seeks to address all the above issues, although this paper focuses on our initial work on trust specification and analysis.
---
paper_title: Analysing the Relationship between Risk and Trust

paper_content:

Among the various human factors impinging upon making a decision in an uncertain environment, risk and trust are surely crucial ones. Several models for trust have been proposed in the literature but few explicitly take risk into account. This paper analyses the relationship between the two concepts by first looking at how a decision is made to enter into a transaction based on the risk information. We then draw a model of the invested fraction of the capital function of a decision surface. We finally define a model of trust composed of a reliability trust as the probability of transaction success and a decision trust derived from the decision surface.
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paper_title: "Trust me, I'm an online vendor": towards a model of trust for e-commerce system design

paper_content:

Consumers' lack of trust has often been cited as a major barrier to the adoption of electronic commerce (e-commerce). To address this problem, a model of trust was developed that describes what design factors affect consumers' assessment of online vendors' trustworthiness. Six components were identified and regrouped into three categories: Prepurchase Knowledge, Interface Properties and Informational Content. This model also informs the Human-Computer Interaction (HCI) design of e-commerce systems in that its components can be taken as trust-specific high-level user requirements.
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paper_title: Automated management of inter-organisational applications

paper_content:

Inter-organisational applications require improved support from middleware services. This paper analyses the management requirements of multidomain applications, covering both technological domains and organisations (administrative business domains). The analysis leads to a suggested middleware solution for these needs, presenting a group of cooperative, pervasive management services that use a common, abstract management language suitable for expressing a platform-independent model of cooperation between sovereign components and contracts about selected technologies. The approach is compatible with OMG MDA (Model Driven Architecture) work.
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paper_title: Statistical trustability (conceptual work)

paper_content:

Trust management and trust-aware applications have gained importance in re- cent years (e.g., [1,2]). Conventional security mechanisms are unable to cover all application domains. For example, in ad hoc networks, the frequent lack of an online connection to the Internet makes routine tasks very difficult. Trust seems to be a good way to overcome such shortcomings because it does not necessarily rely on fixed centralized infrastructures [5].
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paper_title: Simulating the Effect of Reputation Systems on E-markets

paper_content:

Studies show that reputation systems have the potential to improve market quality. In this paper we report the results of simulating a market of trading agents that uses the beta reputation system for collecting feedback and computing agents' reputations. The simulation confirms the hypothesis that the presence of the reputation system improves the quality of the market. Among other things it also shows that a market with limited duration rather than infinite longevity of transaction feedback provides the best conditions under which agents can adapt to each others change in behaviour.
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paper_title: A Case for Evidence-Aware Distributed Reputation Systems: Overcoming the Limitations of Plausibility Considerations

paper_content:

Reputation systems support trust formation in artificial societies by keeping track of the behavior of autonomous entities. In the absence of any commonly trusted entity, the reputation system has to be distributed to the autonomous entities themselves. They may cooperate by issuing recommendations of other entities’ trustworthiness. At the time being, distributed reputation systems rely on plausibility for assessing the truthfulness and consistency of such recommendations. In this paper, we point out the limitations of such plausibility considerations and present an alternative concept that is based on evidences. The concept combines the strengths of non-repudiability and distributed reputation systems. We analyze the issues that are related to the issuance and gathering of evidences. In this regard, we identify four patterns of how evidence-awareness overcomes the limitations of plausibility considerations.
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paper_title: Implementation of an Agent-Oriented Trust Management Infrastructure Based on a Hybrid PKI Model

paper_content:

Access control in modern computing environments is different from access control in the traditional setting of operating systems. For distributed computing systems, specification and enforcement of permissions can be based on a public key infrastructure which deals with public keys for asymmetric cryptography. Previous approaches and their implementations for applying a public key infrastructure are classified as based either on trusted authorities with licencing or on owners with delegations. We present the architecture and main features of a trust management infrastructure based on a hybrid model which unifies and extends the previous public key infrastructure approaches. The trust management infrastructure constitutes a flexible framework for experimenting with the applications of different trust models.
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paper_title: A trust matrix model for electronic commerce

paper_content:

We propose a so-called trust matrix model to build trust for conducting first trade transactions in electronic commerce; i.e. transactions in an electronic commerce environment between two parties that have never conducted trade transactions between them before. The trust matrix model is based on the idea that for business-to-business electronic commerce a balance has to be found between anonymous procedural trust, i.e. procedural solutions for trust building, and personal trust based on positive past experiences within an existing business relation. Procedural trust building solutions are important for first trade situations, because of the lack of experience in these situations. The procedural trust solutions are related to the notion of institution-based trust, because the trust in the procedural solutions depends on the trust one has in the institutions that issued or enforces the procedure. The trust matrix model can be used as a tool to analyze and develop trust-building services to help organizations conduct first-trade electronic commerce transactions.
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paper_title: Challenges for trust, fraud and deception research in multi-agent systems

paper_content:

Discussions at the 5th Workshop on Deception, Fraud and Trust in Agent Societies held at the 1st International Joint Conference on Autonomous Agents and Multi-Agent Systems (AAMAS 2002) centered around many important research issues1. This paper attempts to challenge researchers in the community toward future work concerning three issues inspired by the workshop's roundtable discussion: (1) distinguishing elements of an agent's behavior that influence its trustworthiness, (2) building reputation-based trust models without relying on interaction, and (3) benchmarking trust modeling algorithms. Arguments justifying the validity of each problem are presented, and benefits from their solutions are enumerated.
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paper_title: Pinocchio: Incentives for Honest Participation in Distributed Trust Management

paper_content:

In this paper, we introduce a framework for providing incentives for honest participation in global-scale distributed trust management infrastructures. Our system can improve the quality of information supplied by these systems by reducing free-riding and encouraging honesty. Our approach is twofold: (1) we provide rewards for participants that advertise their experiences to others, and (2) impose the credible threat of halting the rewards, for a substantial amount of time, for participants who consistently provide suspicious feedback. For this purpose we develop an honesty metric which can indicate the accuracy of feedback.
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paper_title: An Intrusion-Detection Model

paper_content:

A model of a real-time intrusion-detection expert system capable of detecting break-ins, penetrations, and other forms of computer abuse is described. The model is based on the hypothesis that security violations can be detected by monitoring a system's audit records for abnormal patterns of system usage. The model includes profiles for representing the behavior of subjects with respect to objects in terms of metrics and statistical models, and rules for acquiring knowledge about this behavior from audit records and for detecting anomalous behavior. The model is independent of any particular system, application environment, system vulnerability, or type of intrusion, thereby providing a framework for a general-purpose intrusion-detection expert system.
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paper_title: Specification-based anomaly detection: a new approach for detecting network intrusions

paper_content:

Unlike signature or misuse based intrusion detection techniques, anomaly detection is capable of detecting novel attacks. However, the use of anomaly detection in practice is hampered by a high rate of false alarms. Specification-based techniques have been shown to produce a low rate of false alarms, but are not as effective as anomaly detection in detecting novel attacks, especially when it comes to network probing and denial-of-service attacks. This paper presents a new approach that combines specification-based and anomaly-based intrusion detection, mitigating the weaknesses of the two approaches while magnifying their strengths. Our approach begins with state-machine specifications of network protocols, and augments these state machines with information about statistics that need to be maintained to detect anomalies. We present a specification language in which all of this information can be captured in a succinct manner. We demonstrate the effectiveness of the approach on the 1999 Lincoln Labs intrusion detection evaluation data, where we are able to detect all of the probing and denial-of-service attacks with a low rate of false alarms (less than 10 per day). Whereas feature selection was a crucial step that required a great deal of expertise and insight in the case of previous anomaly detection approaches, we show that the use of protocol specifications in our approach simplifies this problem. Moreover, the machine learning component of our approach is robust enough to operate without human supervision, and fast enough that no sampling techniques need to be employed. As further evidence of effectiveness, we present results of applying our approach to detect stealthy email viruses in an intranet environment.
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paper_title: Adaptive real-time anomaly detection using inductively generated sequential patterns

paper_content:

A time-based inductive learning approach to the problem of real-time anomaly detection is described. This approach uses sequential rules that characterize a user's behavior over time. A rulebase is used to store patterns of user activities, and anomalies are reported whenever a user's activity deviates significantly from those specified in the rules. The rules in the rulebase characterize either the sequential relationships between security audit records or the temporal properties of the records. The rules are created in two ways: they are either dynamically generated and modified by a time-based inductive engine in order to adapt to changes in a user's behavior, or they are specified by the security management to implement a site security policy. This approach allows the correlation between adjacent security events to be exploited for the purpose of greater sensitivity in anomaly detection against seemingly intractable (or erratic) activities using statistical approaches. Real-time detection of anomaly activities is possible. >
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paper_title: A sense of self for Unix processes

paper_content:

A method for anomaly detection is introduced in which ``normal'' is defined by short-range correlations in a process' system calls. Initial experiments suggest that the definition is stable during normal behavior for standard UNIX programs. Further, it is able to detect several common intrusions involving sendmail and lpr. This work is part of a research program aimed at building computer security systems that incorporate the mechanisms and algorithms used by natural immune systems.
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paper_title: Using Internal Sensors For Computer Intrusion Detection

paper_content:

This dissertation introduces the concept of using internal sensors to perform intrusion detection in computer systems. It shows its practical feasibility and discusses its characteristics and related design and implementation issues. ::: We introduce a classification of data collection mechanisms for intrusion detection systems. At a conceptual level, these mechanisms are classified as direct and indirect monitoring. At a practical level, direct monitoring can be implemented using external or internal sensors. Internal sensors provide advantages with respect to reliability, completeness, timeliness and volume of data, in addition to efficiency and resistance against attacks. ::: We introduce an architecture called ESP as a framework for building intrusion detection systems based on internal sensors. We describe in detail a prototype implementation based on the ESP architecture and introduce the concept of embedded detectors as a mechanism for localized data reduction. ::: We show that it is possible to build both specific (specialized for a certain intrusion) and generic (able to detect different types of intrusions) detectors. Furthermore, we provide information about the types of data and places of implementation that are most effective in detecting different types of attacks. ::: Finally, performance testing of the ESP implementation shows the impact that embedded detectors can have on a computer system. Detection testing shows that embedded detectors have the capability of detecting a significant percentage of new attacks.
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paper_title: Trust-adapted enforcement of security policies in distributed component-structured applications

paper_content:

Software component technology on the one hand supports the cost-effective development of specialized applications. On the other hand, however it introduces special security problems. Some major problems can be solved by the automated run-time enforcement of security policies. Each component is controlled by a wrapper which monitors the component's behavior and checks its compliance with the security behavior constraints of the component's employment contract. Since control functions and wrappers can cause substantial overhead, we introduce trust-adapted control functions where the intensity of monitoring and behavior checks depends on the level of trust, the component, its hosting environment, and its vendor have currently in the eyes of the application administration. We report on wrappers and a trust information service, outline the embedding security model and architecture, and describe a Java Bean based experimental implementation.
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paper_title: Using trust for secure collaboration in uncertain environments

paper_content:

The SECURE project investigates the design of security mechanisms for pervasive computing based on trust. It addresses how entities in unfamiliar pervasive computing environments can overcome initial suspicion to provide secure collaboration.
---
paper_title: A computational model of trust and reputation

paper_content:

Despite their many advantages, e-businesses lag behind brick and mortar businesses in several fundamental respects. This paper concerns one of these: relationships based on trust and reputation. Recent studies on simple reputation systems for e-Businesses such as eBay have pointed to the importance of such rating systems for deterring moral hazard and encouraging trusting interactions. However, despite numerous studies on trust and reputation systems, few have taken studies across disciplines to provide an integrated account of these concepts and their relationships. This paper first surveys existing literatures on trust, reputation and a related concept: reciprocity. Based on sociological and biological understandings of these concepts, a computational model is proposed. This model can be implemented in a real system to consistently calculate agents' trust and reputation scores.
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paper_title: Specifying and Analysing Trust for Internet Applications

paper_content:

The Internet is now being used for commercial, social and educational interactions, which previously relied on direct face-to-face contact in order to establish trust relationships. Thus, there is a need to be able to establish and evaluate trust relationships relying only on electronic interactions over the Internet. A trust framework for Internet applications should incorporate concepts such as experience, reputation and trusting propensity in order to specify and evaluate trust. SULTAN (Simple Universal Logic-oriented Trust Analysis Notation) is an abstract, logic-oriented notation designed to facilitate the specification and analysis of trust relationships. SULTAN seeks to address all the above issues, although this paper focuses on our initial work on trust specification and analysis.
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paper_title: Enhanced Reputation Mechanism for Mobile Ad Hoc Networks

paper_content:

Interactions between entities unknown to each other are inevitable in the ambient intelligence vision of service access anytime, anywhere. Trust management through a reputation mechanism to facilitate such interactions is recognized as a vital part of mobile ad hoc networks, which features lack of infrastructure, autonomy, mobility and resource scarcity of composing light-weight terminals. However, the design of a reputation mechanism is faced by challenges of how to enforce reputation information sharing and honest recommendation elicitation. In this paper, we present a reputation model, which incorporates two essential dimensions, time and context, along with mechanisms supporting reputation formation, evolution and propagation. By introducing the notion of recommendation reputation, our reputation mechanism shows effectiveness in distinguishing truth-telling and lying agents, obtaining true reputation of an agent, and ensuring reliability against attacks of defame and collusion.
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paper_title: SULTAN-A Language for Trust Specification and Analysis

paper_content:

A precast unit, preferably of cementitious material, of circular outline having stone-like block units on the outer surface separated by mortar joints and top shoulder annular portions to serve as a guide to enable stacking like units above each other. The inner surface of each unit and outer surface of each projection extend in a downwardly and outwardly extending direction to provide a stepped inner wall.
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paper_title: Engineering Trust Based Collaborations in a Global Computing Environment

paper_content:

Trust management seems a promising approach for dealing with security concerns in collaborative applications in a global computing environment. However, the characteristics of this environment require a move from reliable identification to mechanisms for the recognition of entities. Furthermore, they require explicit reasoning about the risks of interactions, and a notion of uncertainty in the underlying trust model. From our experience of engineering collaborative applications in such an environment, we found that the relationship between trust and risk is a fundamental issue. In this paper, as an initial step towards an engineering approach for the development of trust based collaborative applications, we focus on the relationship between trust and risk, and explore alternative views of this relationship. We also exemplify how particular views can be exploited in two particular application scenarios. This paper builds upon our previous work in developing a general model for trust based collaborations.
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paper_title: A computational model of trust and reputation

paper_content:

Despite their many advantages, e-businesses lag behind brick and mortar businesses in several fundamental respects. This paper concerns one of these: relationships based on trust and reputation. Recent studies on simple reputation systems for e-Businesses such as eBay have pointed to the importance of such rating systems for deterring moral hazard and encouraging trusting interactions. However, despite numerous studies on trust and reputation systems, few have taken studies across disciplines to provide an integrated account of these concepts and their relationships. This paper first surveys existing literatures on trust, reputation and a related concept: reciprocity. Based on sociological and biological understandings of these concepts, a computational model is proposed. This model can be implemented in a real system to consistently calculate agents' trust and reputation scores.
---
paper_title: Enhanced Reputation Mechanism for Mobile Ad Hoc Networks

paper_content:

Interactions between entities unknown to each other are inevitable in the ambient intelligence vision of service access anytime, anywhere. Trust management through a reputation mechanism to facilitate such interactions is recognized as a vital part of mobile ad hoc networks, which features lack of infrastructure, autonomy, mobility and resource scarcity of composing light-weight terminals. However, the design of a reputation mechanism is faced by challenges of how to enforce reputation information sharing and honest recommendation elicitation. In this paper, we present a reputation model, which incorporates two essential dimensions, time and context, along with mechanisms supporting reputation formation, evolution and propagation. By introducing the notion of recommendation reputation, our reputation mechanism shows effectiveness in distinguishing truth-telling and lying agents, obtaining true reputation of an agent, and ensuring reliability against attacks of defame and collusion.
---
paper_title: SULTAN-A Language for Trust Specification and Analysis

paper_content:

A precast unit, preferably of cementitious material, of circular outline having stone-like block units on the outer surface separated by mortar joints and top shoulder annular portions to serve as a guide to enable stacking like units above each other. The inner surface of each unit and outer surface of each projection extend in a downwardly and outwardly extending direction to provide a stepped inner wall.
---

Title: Trust Management Survey

Section 1: Introduction
Description 1: Introduce the importance and challenges of trust management, and outline the structure of the paper.

Section 2: On the Nature of Trust
Description 2: Provide a brief overview of the trust phenomenon from a sociological perspective.

Section 3: Concepts for Trust Management
Description 3: Discuss trust as it is directed at independent actors and the factors affecting trust decisions.

Section 4: The Trust Management Model
Description 4: Explore the roots of trust management in authentication and authorization and its evolution into dynamic trust models.

Section 5: The Trust Information Model
Description 5: Examine the representation of trust, reputation, and related concepts in computer systems.

Section 6: The Tasks of a Trust Management System
Description 6: Identify the main challenges for trust management systems, including initialization, observation, and action based on trust decisions.

Section 7: Initializing a Trust Relationship
Description 7: Discuss methods for determining initial trust and the role of reputation systems.

Section 8: Observation
Description 8: Explore techniques for monitoring trustee behavior, including the use of intrusion detection systems.

Section 9: Evolving Reputation and Trust
Description 9: Describe how reputation and trust are updated based on observed behavior and gathered experience.

Section 10: Conclusions
Description 10: Summarize the findings, highlight the challenges, and suggest areas for future research in trust management.