Year: 2010
Type: dissertation
Abstract: Building trust is a common requirement in distributed environments especially \nsince many transactions now occur on a person-to-person basis. Examples range \nfrom e-commerce on the Internet to peer-to-peer and grid resource sharing. Many \nsolutions to the problem of requiring trust among unknown entities rely on the use \nof a reputation metric to assess the risk of a potential transaction. However, such \nreputation systems require (often implicitly) that trust is transitive which can be a problematic assumption. \nThis dissertation proposes a novel mechanism which we call trust*. The trust* model uses guarantees to extend local trust between unknown end-points. Trust* can be used as a substitution for end-to-end trust. Principals provide guarantees within existing (local) trust relationships to build a chain of localised agreements \nbetween the unknown end-points. The guarantees are backed by local micropayments \nto provide deterrents and incentives. Trust* relationships can be composed transitively, and the guarantees reduce the risk for the trusting party when doing so. This is because a guarantee is only ever provided locally by a directly trusted principal. Thus, trust management can be reduced to a locally solved problem. \nThis work aims to develop a new technique for assessing and reducing the risk involved in trusting others in a distributed environment. The thesis of this dissertation is that an electronic analogue of real-world guarantees, is a useful and interesting way to provide these assurances. We develop an extension of the notion of trust, which we call trust*, which is built upon local guarantees, and which provides a novel conceptual framework for analysing and reasoning about a wide variety of trust-related problems in distributed systems. \nWe present the concept of trust* and apply it to a number of application scenarios where it would be beneficial. We simulate the trust* model in these environments \nfor analysis. Also, we describe the key features and other issues related \nto the trust* model which became evident during its investigation and which are \nof wider interest.
Author: Stephen Clarke
Language: English
Topic: Access Control and Trust
Subfield: Computer Networks and Communications
Field: Computer Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2168923231