Research On Mechanism Of Automated Trust Establishment In Open Systems

Due to recent Internet trends, large-scale open systems in which resources are shared across organizational boundaries are becoming ever more popular. Differing from traditional distributed systems, open systems possess resources accessible for public instead of only for a specifical group. Traditional identity-based security mechanism fails to resolve the security problems in open systems because a potentially unbounded number of users exist in systems and there is no pre-existing trust relationship between users and systems. Aiming to help solve the problems surrounding automated trust establishment in open systems, automated trust negotiation attracts many researchers and becomes an active area of research. At present, many noticeable works have been done about automated trust negotiation. However, in order to widely deploy automated trust negotiation, many challenging issues need to be addressed. These issues include effective applied trust negotiation model, the interoperability between trust negotiation systems, attacks and defenses in automated trust negotiation, and so on. Our research spreads out in accordance with the issues above, and concrete achievements mainly involve the following aspects.On trust negotiation model, this paper analyzes the insufficiencies that the existing trust negotiation model could result in leaking user's sensitive information and confidential information about access control policy, and negotiation protocol is designed to be so complicated that negotiation works inefficient. To enhance the practicality of trust negotiation systems, an agent-based automated trust negotiation mechanism (A2TNM) is proposed. A2TNM introduces the agent to separate trust negotiation from the concrete application and supplies it for public as a network service. Meanwhile, A2TNM specifies the format of a Meta access control policy, and adopts credentials with flexible format to meet the requirements of access control policies, instead of disclosing the whole contents of a certificate. Furthermore, A2TNM uses asymmetric functions with a high security intensity to encrypt the transmitting message, which can prevent information from being attacked. Finally, A2TNM presents a new negotiation protocol to guide the negotiation process. A use case is studied to illuminate that A2TNM is sound and reasonable. Compared with existing works, the intelligence, privacy and negotiation efficiency are improved in A2TNM.The interoperability of automated trust negotiation system is in relation to the adoption of negotiation strategy and negotiation protocol. On the interoperability of negotiation strategy, a model of trust negotiation is proposed that gives entities autonomy in choosing whatever strategies meet their requirements. Then necessary and sufficient conditions are identified for a successful negotiation when two parties adopt different strategies. A set of strategies is designed and proved that two parties can always establish trust whenever their access control policies allow, if they are using any two strategies from the set. It is showed that the set of strategies provides users maximal flexibility in choosing strategies that fit their requirements for trust negotiation.On the generality of negotiation protocol, a strategy-independent trust negotiation protocol is presented. In the protocol, message is classified into three categories:resource request message, information disclosure message and ending negotiation message, and their form is defined. Three states of the negotiation process and the transformation between them are illustrated, and the protocol algorithm is expressed by pseudo codes. The analysis indicates that, the protocol supports the disclosure of digital assertions including credentials with various formats and access policies specified with different policy languages, and allows adopting manifold strategies in a negotiation process, and satisfies to negotiate in various application scenes, and is provided with distinct generality as a result.On the attacks and defenses in automated trust negotiation, a comprehensive survey of research on attacks in ATN is presented based on the classification and introduction of different attacking manners and corresponding defenses, the shortcomings of the current related research is pointed out and the development trend is also discussed.