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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Supporting trust in virtual communities

Trust is an important aspect of decision making for Internet applications and particularly influences the specification of security policy, i.e., who is authorized to perform actions as well as the techniques needed to manage and implement security to and for the applications. This survey examines the various definitions of trust in the literature and provides a working definition of trust for Internet applications. The properties of trust relationships are explained and classes of different types of trust identified in the literature are discussed with examples. Some influential examples of trust management systems are described.

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A survey of trust in internet applications

In this paper we present a survey of secure ad hoc routing protocols for mobile wireless networks. A mobile ad hoc network is a collection of nodes that is connected through a wireless medium forming rapidly changing topologies. The widely accepted existing routing protocols designed to accommodate the needs of such self-organized networks do not address possible threats aiming at the disruption of the protocol itself. The assumption of a trusted environment is not one that can be realistically expected; hence several efforts have been made towards the design of a secure and robust routing protocol for ad hoc networks. We briefly present the most popular protocols that follow the table-driven and the source-initiated on-demand approaches. Based on this discussion we then formulate the threat model for ad hoc routing and present several specific attacks that can target the operation of a protocol. In order to analyze the proposed secure ad hoc routing protocols in a structured way we have classified them into five categories; solutions based on asymmetric cryptography, solutions based on symmetric cryptography, hybrid solutions, reputation-based solutions and a category of add-on mechanisms that satisfy specific security requirements. A comparison between these solutions can provide the basis for future research in this rapidly evolving area.

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Secure routing for mobile ad hoc networks

DDoS attacks and defense mechanisms: classification and state-of-the-art

Web-based social networks have become popular as a medium for disseminating information and connecting like-minded people. The public accessibility of such networks with the ability to share opinions, thoughts, information, and experience offers great promise to enterprises and governments. In addition to individuals using such networks to connect to their friends and families, governments and enterprises have started exploiting these platforms for delivering their services to citizens and customers. However, the success of such attempts relies on the level of trust that members have with each other as well as with the service provider. Therefore, trust becomes an essential and important element of a successful social network. In this article, we present the first comprehensive review of social and computer science literature on trust in social networks. We first review the existing definitions of trust and define social trust in the context of social networks. We then discuss recent works addressing three aspects of social trust: trust information collection, trust evaluation, and trust dissemination. Finally, we compare and contrast the literature and identify areas for further research in social trust.

A survey of trust in social networks

One of the great strengths of public-key cryptography is its potential to allow the localization of trust. This potential is greatest when cryptography is present to guarantee data integrity rather than secrecy, and where there is no natural hierarchy of trust. Both these conditions are typically fulfilled in the commercial world, where CSCW requires sharing of data and resources across organizational boundaries. One property which trust is frequently assumed or “proved” to have is transitivity (if A trusts B and B trusts C then A trusts C) or some generalization of transitivity such as *-closure. We use the loose term unintensional transitivity of trust to refer to a situation where B can effectively put things into A's set of trust assumptions without A's explicit consent (or sometimes even awareness.) Any account of trust which allows such situations to arise clearly poses major obstacles to the effective confinement (localization) of trust. In this position paper, we argue against the need to accept unintensional transitivity of trust. We distinguish the notion of trust from a number of other (transitive) notions with which it is frequently confused, and argue that “proofs” of the unintensional transitivity of trust typically involve unpalatable logical assumptions as well as undesirable consequences.

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Why Isn't Trust Transitive?

From the Publisher:
This book constitutes the strictly refereed post-workshop proceedings of the 5th International Workshop on Security Protocols, held in Paris, France, in April 1997. The 17 revised full papers presented address all current aspects of security protocols. Among the topics covered are secure distribution of knowledge, electronic voting systems, secure Internet transactions, digital signatures, key exchange, cryprographic protocols, authentication, threshold systems, secret sharing, ect. The 17 revised full papers presented address all current aspects of security protocols. Among the topics covered are secure distribution of knowledge, electronic voting systems, secure Internet transactions, digital signatures, key exchange, cryprographic protocols, authentication, threshold systems, secret sharing, ect.

Proceedings of the 5th International Workshop on Security Protocols

Delegating trust. We do use these words, we keep going back to them, you know, what is trust, what is delegation. I’m sure it will come to a great relief to many of you that I’m not going to talk too much about trust but I would like to point out that in common with many of the terms we use in security, there doesn’t seem to be any general agreement on what it is. There’s the orange book definition: a component of the system that can violate the security of the system. There are uses of trust that are indistinguishable from belief. There are attempts not to use the word at all. I have my own definition, but I won’t bore you with that today. Needless to say though, this does cause confusion. It’s almost unavoidable that we use the term but what I thought I would talk about today is the relationship between trust and delegation, because I think there is a relationship. As a brief introduction I made a note of something that Joan said yesterday. She was talking about whether she would trust somebody to do something for her, and I believe in this context she was going to trust Steve Bellovin to sort out something for her. It merely occurred to me that when you talk about trusting somebody to do something for you in that way you are in fact delegating responsibility for that task to them. So I think there is a very strong relationship between trust and delegation and they are sometimes used, as Joan did yesterday, interchangeably. I think we do need to be cautious about how they’re used, when they’re used, and to try to get a little precision, We all start here the dictionary definition. This just happens to be the one we had in the office: “gives duties, powers, etc. to another as a representative to depute or to authorise somebody as a representative.” They are actually different things of course, and I think we will see that as we come on. I thought, well perhaps we ought to say something about why it’s important. I mean, why is delegation important? Well I think it’s important because we can’t avoid it. We’re always delegating all the time. Sometimes knowingly, often unknowingly, we use the system to perform a task for us, you could view that as delegating the task to the system, and so I think it does bear some looking into what we’re doing, how we’re doing it, why we’re doing it, and whether what we’re doing is always the same thing. Why do we delegate? Well, here are some of the reasons we might. Only we can perform the function for some reason, and therefore if for some reason we’re not there, or we want to do something about it, delegate it. We delegate because someone else has a particular expertise or a particular facility that we don’t have but which we need in order to complete the task we’re doing. We may delegate

Delegating Trust (Transcript of Discussion)

Although the notion of negotiation has been used extensively in secure communication protocols to establish common keying states, protocol modes and services, this notion is only now emerging in the area of access control policies. In this paper, we review the motivation for access policy negotiation and we provide some examples of use in practice. In particular, we illustrate the meaning, the types, and the process of negotiation for establishing common access states and common interpretations of policy models for dynamic coalitions and large-scale access control in the Internet.

William S. Harbison

Papers

Why Isn't Trust Transitive?

Proceedings of the 5th International Workshop on Security Protocols

Delegating Trust (Transcript of Discussion)

On the negotiation of access control policies. Discussion