A collaborative trust calculation scheme for cloud computing systems

One of the major hurdles in the widespread use of cloud computing systems is the lack of trust between consumer and service provider. Lack of trust can put consumer´s sensitive data and applications at risk. Consumers need assurance that service providers will provide services as per agreement and will not deviate from agreed terms and conditions. Though trust is a subjective term, it can be measured objectively also. In this paper we present the design and simulation of a collaborative trust calculation scheme in which trust on a service provider is build by participants in a collaborative way. Each collaborator shares its experience of service provider with the coordinator and then shared experiences are aggregated by coordinator to compute final trust value which represents the trustworthiness of service provider. The scheme makes use of fuzzy logic to aggregate responses and to handle uncertain and imprecise information. Collaborative trust calculation scheme makes it difficult for untrustworthy service provider to build its reputation in the system by providing quality services only to a selected set of participants. A service provider has to provide agreed services to all participants uniformly in order to build reputation in the environment. Simulation has been done using MATLAB toolkit. Simulation results show that the scheme is workable and can be adopted for use in collaborative cloud computing systems to determine trustworthiness of service providers.