Design and Comparative Analysis of MCDM-based Multi-dimensional Trust Evaluation Schemes for Determining Trustworthiness of Cloud Service Providers

This paper presents the design and comparative analysis of MCDM-based multi-dimensional trust evaluation schemes for determining trustworthiness of Cloud Service Providers (CSPs) in a cloud environment. The trustworthiness has been defined as the degree of compliance provided by a CSP to the promised QoS parameters as per the Service Level Agreement (SLA). Due to large number of CSPs offering similar kinds of services in a cloud environment, it has become a challenging task for Cloud Clients (CCs) to identify and differentiate between trustworthy and untrustworthy CSPs. We present the design and comparative analysis of three MCDM-based techniques (AHP, TOPSIS and PROMETHEE) that enable CCs to determine the trustworthiness of a CSP from different perspectives. All the three schemes enable us to assess the trustworthiness of a CSP from CC's perspective, Cloud Auditor's perspective, Cloud Broker's perspective and Peers' perspective. Experimental results show that all the techniques are effective and stable in differentiating between trustworthy and untrustworthy CSPs. The PROMETHEE technique has shown advantage over the AHP and the TOPSIS methods in the sense that it has reported less uncertainty during evaluations. The applicability and validity of the schemes have been demonstrated with the help of a case study involving the use of real cloud data.