Bridging the gap between human and machine trust : applying methods of user-centred design and usability to computer security

This work presents methods for improving the usability of security. The work focuses on trust as part of computer security. Methods of usability and user-centred design present an essential starting point for the research. The work uses the methods these fields provide to investigate differences between machine and human trust, as well as how the technical expressions of trust could be made more usable by applying these methods. The thesis is based on nine publications, which present various possibilities to research trust with user-centric methods. The publications proceed chronologically and logically from the first user interviews about trust, trusting attitudes and behaviours in general to the actual design and usability testing of user interfaces for security applications, finally presenting the outcomes and conclusions of the research. The work also presents a review of relevant previous work in the area, concentrating on work done in the fields of usability and user-centred design. The work is of cross-disciplinary nature, falling into the areas of human-computer interaction, computer science and telecommunications. The ultimate goal of the conducted research has been to find out 1) how trust is to be understood in this context; 2) what methods can be used to gain insight into trust thus defined; and, finally, 3) what means can be used to create trust in the end users in online situations, where trust is needed. The work aims at providing insight into how trust can be studied with the methods provided by user-centred design and usability. Further, it investigates how to take understanding of trust formation in humans into account when attempting to design trust-inducing systems and applications. The work includes an analysis and comparison of the methods used: what kinds of methods to study trust exist in the field of usability and user-centred design. Further, it is evaluated, what kind of results and when can be reached with the different methods available, by applying a variety of these methods. Recommendations for the appropriate application of these methods when studying the various parts of trust is one of the outcomes. The results received with the methods used have also been compared with results received by others by applying alternative methods to the same research questions. On a conceptual level, the work contains an analysis of the concept of trust. It also contains a brief investigation into both technical and humane ways to express trust, with a comparison between the two

Naming and sharing resources across administrative boundaries

I tackle the problem of naming and sharing resources across administrative boundaries. Conventional systems manifest the hierarchy of typical administrative structure in the structure of their own mechanism. While natural for communication that follows hierarchical patterns, such systems interfere with naming and sharing that cross administrative boundaries, and therefore cause headaches for both users and administrators. I propose to organize resource naming and security, not around administrative domains, but around the sharing patterns of users. The dissertation is organized into four main parts. First, I discuss the challenges and tradeoffs involved in naming resources and consider a variety of existing approaches to naming. Second, I consider the architectural requirements for user-centric sharing. I evaluate existing systems with respect to these requirements. Third, to support the sharing architecture, I develop a formal logic of sharing that captures the notion of restricted delegation. Restricted delegation ensures that users can use the same mechanisms to share resources consistently, regardless of the origin of the resource, or with whom the user wishes to share the resource next. A formal semantics gives unambiguous meaning to the logic. I apply the formalism to the Simple Public Key Infrastructure and discuss how the formalism either supports or discourages potential extensions to such a system. Finally, I use the formalism to drive a user-centric sharing implementation for distributed systems. I show how this implementation enables end-to-end authorization, a feature that makes heterogeneous distributed systems more secure and easier to audit. Conventionally, gateway services that bridge administrative domains, add abstraction, or translate protocols typically impede the flow of authorization information from client to server. In contrast, end-to-end authorization enables us to build gateway services that preserve authorization information, hence we reduce the size of the trusted computing base and enable more effective auditing. I demonstrate my implementation and show how it enables end-to-end authorization across various boundaries. I measure my implementation and argue that its performance tracks that of similar authorization mechanisms without end-to-end structure. I conclude that my user-centric philosophy of naming and sharing benefits both users and administrators

Protecting the infrastructure: 3rd Australian information warfare & security conference 2002

The conference is hosted by the We-B Centre (working with a-business) in the School of Management Information System, the School of Computer & Information Sciences at Edith Cowan University. This year\u27s conference is being held at the Sheraton Perth Hotel in Adelaide Terrace, Perth. Papers for this conference have been written by a wide range of academics and industry specialists. We have attracted participation from both national and international authors and organisations. The papers cover many topics, all within the field of information warfare and its applications, now and into the future. The papers have been grouped into six streams: • Networks • IWAR Strategy • Security • Risk Management • Social/Education • Infrastructur

Certifying Trust

A basic function of all signatures, digital or not, is to express trust and authority, explicit or implied. This is especially the case with digital signatures used in certificates. In this paper, we study the trust relationships expressed by the certificates used in X.509, PGP and SPKI. Especially, we present and revise the idea of a certificate loop, or a loop of certificates from the verifying party to the communicating peer, requesting access or acceptance. We also show how that kind of certificate loops can be used to explicitly express security policy decisions. In the en