Distributed trust and reputation management mechanisms are often proposed as a means of providing assurance in dynamic and open environments by enabling principals to building up knowledge of the entities with which they interact. However, there is a tension between the preservation of privacy (which would suggest a refusal to release information) and the controlled release of information that is necessary both in order to accomplish tasks and to provide a foundation for the assessment of trustworthiness. However, if reputation-based systems are to be used in assessing the risks of privacy violation, it is necessary both to discover when sensitive information has been released, and then to be able to evaluate the likelihood that each of the set of principals that knew that information was involved in its release.

The terms pervasive and ubiquitous computing are used to describe a smart space populated by hundreds of intelligent devices that are embedded in their surroundings. Characteristically, ubiquitous computing devices must blend into the background, unobtrusively collaborating to provide valueadded services for users. Services are thus essential to the success of this technology and, as a result, both service discovery and service management will play a vital role in generating the revenue stream that is a prerequisite for sustainable ubiquitous deployment. On the one hand, the services provided should be evident by their richness and variety and on the other, the complexity inherent in the environment must be hidden from users. In this paper, we describe RUBI, a resource discovery framework for ubiquitous computing. RUBI represents a novel approach to resource discovery, because the primacy of the need for adaptive autonomic behaviour is established within its design.

In all computer systems, interactions between parties require the establishment of a level of trust that is determined to be sufficient to permit the requested action to take place. Traditionally, such trust has been policed centrally by having authorities that determine whether or not an individual is trustworthy (cf Equifax etc.). To make this work, several premises must hold: (1) there is widespread trust in such authorities (2) the penalties that the central authorities can impose by withdrawing their sanction are sufficiently severe as to discourage bad behaviour (3) it is not possible for individuals to easily change their identity to avoid such penalties..

Keywords: Trust, game theory, risk, ubiquitous

The comfortable certainties about the nature of trust on which most conventional security systems have been founded have always been at best doubtful. In pervasive computing environments they become both delusional and dangerous. As a consequence, it is necessary for both technically aware service providers and technically na?1ve end users to abandon the false hope that the behaviour of secure pervasive systems can ever be predictable or repeatable; they must learn to accept the same degree of uncertainty in trust for their digital identities as they implicitly accept in their everyday human relationships. Computing technology is disappearing into the environment in a realisation of Mark Weiser s vision for ubiquitous (pervasive) computing. In the near future, the collision of the Internet with the embedded systems will mean a massive increase in both scale and heterogeneity of networks. Security is absolutely essential to making this a reality, but conventional security measures have little hope of working; the centralised control of security, relying on the a priori definition of the role, authority and relationships between principals is both undesirable and unsustainable in such environments. In this paper, we explore the need for security in pervasive systems, the difficulties in providing it, and ways in which sociological models of trust management map into the digital world. We will present ADAM a means of enabling the automation of trust establishment and maintenance through distributed knowledge acquisition and management over a self-organised collection of agents. These agents collect and collate information based on experience and recommendations from different sources and thereby enable trusting decisions to be taken.

This work discusses a conceptual model for automatic acquisition and processing of knowledge about users and devices in computer networks. It employs autonomous agents for distributed knowledge management. Agents grouped into distributed communities act as mediators between users, devices, and network resources. Communicating between each other they make decisions on whether a certain user or device can be given access to a requested resource. In other words, agents in our system perform user/device authentication, authorisation, and maintenance of user credentials.

Keywords: Trust, Access Control, Knowledge Management, Autonomous Agents, Distributed Architectures

The conceptual architecture of the access control system described here is based on automatic distributed acquisition and processing of knowledge about users and device s in computer networks. It uses autonomous agents for distributed knowledge management. Agents grouped into distributed communities act as mediators between users/devices and network resources. Communicating with each other, they make decisions about whether a certain user or device can be given access to a requested resource. In other words, agents in our system perform user/device authentication, authorisation, and maintenance of user credentials.

This paper outlines a conceptual architecture for an autonomic middleware component designed to provide application-independent access control for use in largescale highly-dynamic computing environments. In such environments, most notably ambient/pervasive computing environments, centralised access control policy determination is impossible or inadvisable because of the complexity of trust relationships. In the absence of centralisation, network resources are forced to make trusting decisions locally, in the light of information that they themselves can gather. Thus the architecture that is described in this paper is founded around an automatic knowledge acquisition and processing mechanism, acting as the foundations of a semi-autonomous multi-agent system (MAS). The agents dynamically organise themselves into cooperating distributed communities that mediate between users and devices (collectively known as trustees) and network resources (principals). Once activated by their owners, agents maintain user credentials, negotiate amongst themselves to establish the credibility of prospective trustees identities and cooperate to gather evidence about the likelihood of trustees adhering to the policies of principals.

Keywords: Key Words Trust, authorisation, access control, ambient, autonomic

The pervasive environment implies a massive increase in the scale of systems, the heterogeneity of devices and diversity in services available, making the complex task of centrally managing the environment unfeasible. The scope and role of trusted third parties in facilitating trust is also reduced because of the high number of bilateral trust relationships, which cannot be predefined and managed statically. Moreover, the dynamic, mobile and asynchronous nature of many of the devices means that it is difficult to predict their state or context of operation from moment to moment. All this adds up to increased uncertainty and a need for a revision of the methods and concepts used to express and assess trust and provide assurance. This work addresses this need by defining realistic models of digital trust that are capable of dealing with the uncertainties inherent in the environment and that are aware of the contexts of interactions in evaluating trust.