A novel trust management framework for multi-cloud environments based on trust service providers

In this paper, we address the problem of trust management in multi-cloud environments using a trust management architecture based on a group of distributed Trust Service Providers (TSPs). These are independent third-party providers, trusted by Cloud Providers (CPs), Cloud Service Providers (CSPs) and Cloud Service Users (CSUs), that provide trust related services to cloud participants. TSPs are distributed over the clouds, and they elicit raw trust evidence from different sources and in different formats, i.e., adherence of a CSP to a Service Level Agreement (SLA) for a cloud-based service and the feedback sent by CSUs. Using this information, they evaluate the objective trust and subjective trust of CSPs respectively. Furthermore, we introduce a trust propagation network among TSPs across different clouds, which is used by a TSP to obtain trust information about a service from other TSPs. The proposed trust management framework for a multi-cloud environment is based on the proposed trust evaluation model and the trust propagation network. Experiments show that our proposed framework is effective in differentiating trustworthy and untrustworthy CSPs in a multi-cloud environment.