Dynamic trust negotiation for decentralised e-health collaborations

In the Internet-age, the geographical boundaries that have previously impinged upon inter-organisational collaborations have become decreasingly important. Of more importance for such collaborations is the notion and subsequent nature of security and trust - this is especially so in open collaborative environments like the Grid where resources can be both made available, subsequently accessed and used by remote users from a multitude of institutions with a variety of different privileges spanning across the collaboration. In this context, the ability to dynamically negotiate and subsequently enforce security policies driven by various levels of inter-organisational trust is essential. Numerous access control solutions exist today to address aspects of inter-organisational security. These include the use of centralised access control lists where all collaborating partners negotiate and agree on privileges required to access shared resources. Other solutions involve delegating aspects of access right management to trusted remote individuals in assigning privileges to their (remote) users. These solutions typically entail negotiations and delegations which are constrained by organisations, people and the static rules they impose. Such constraints often result in a lack of flexibility in what has been agreed; difficulties in reaching agreement, or once established, in subsequently maintaining these agreements. Furthermore, these solutions often reduce the autonomous capacity of collaborating organisations because of the need to satisfy collaborating partners demands. This can result in increased security risks or reducing the granularity of security policies. Underpinning this is the issue of trust. Specifically trust realisation between organisations, between individuals, and/or between entities or systems that are present in multi-domain authorities. Trust negotiation is one approach that allows and supports trust realisation. The thesis introduces a novel model called dynamic trust negotiation (DTN) that supports n-tier negotiation hops for trust realisation in multi-domain collaborative environments with specific focus on e-Health environments. DTN describes how trust pathways can be discovered and subsequently how remote security credentials can be mapped to local security credentials through trust contracts, thereby bridging the gap that makes decentralised security policies difficult to define and enforce. Furthermore, DTN shows how n-tier negotiation hops can limit the disclosure of access control policies and how semantic issues that exist with security attributes in decentralised environments can be reduced. The thesis presents the results from the application of DTN to various clinical trials and the implementation of DTN to Virtual Organisation for Trials of Epidemiological Studies (VOTES). The thesis concludes that DTN can address the issue of realising and establishing trust between systems or agents within the e-Health domain, such as the clinical trials domain

Towards decentralised security policies for e-health collaborations

No abstract available

Synthesising end-to-end security schemes through endorsement intermediaries

Composing secure interaction protocols dynamically for e-commerce continue to pose a number of challenges, such as lack of standard notations for expressing requirements and the difficulty involved in enforcing them. Furthermore, interaction with unknown entities may require finding common trusted intermediaries. Securing messages sent through such intermediaries require schemes that provide end-to-end security guarantees. In the past, e-commerce protocols such as SET were created to provide such end-to-end guarantees. However, such complex hand crafted protocols proved difficult to model check. This thesis addresses the end-to-end problems in an open dynamic setting where trust relationships evolve, and requirements of interacting entities change over time. Before interaction protocols can be synthesised, a number of research questions must be addressed. Firstly, to meet end-to-end security requirements, the security level along the message path must be made to reflect the requirements. Secondly, the type of endorsement intermediaries must reflect the message category. Thirdly, intermediaries must be made liable for their endorsements. This thesis proposes a number of solutions to address the research problems. End-to-end security requirements were arrived by aggregating security requirements of all interacting parties. These requirements were enforced by interleaving and composing basic schemes derived from challenge-response mechanisms. The institutional trust promoting mechanism devised allowed all vital data to be endorsed by authorised category specific intermediaries. Intermediaries were made accountable for their endorsements by being required to discharge or transfer proof obligations placed on them. The techniques devised for aggregating and enforcing security requirements allow dynamic creation of end-to-end security schemes. The novel interleaving technique devised allows creation of provably secure multiparty schemes for any number of recipients. The structured technique combining compositional approach with appropriate invariants and preconditions makes model checking of synthesised schemes unnecessary. The proposed framework combining endorsement trust with schemes making intermediaries accountable provides a way to alleviate distrust between previously unknown e-commerce entities