Abstract . Cloud computing with its inherent advantages draws attention for business critical applications, but concurrently expects high level of trust in cloud service providers. Reputation-based trust is emerging as a good choice to model trust of cloud service providers based on available evidence. Many existing reputation based systems either ignore or give less importance to uncertainty linked with the evidence. In this paper, we propose an uncertainty model and define our approach to compute opinion for cloud service providers. Using subjective logic operators along with the computed opinion values, we propose mechanisms to calculate the reputation of cloud service providers. We evaluate and compare our proposed model with existing reputation models. Keywords: Cloud, Trust, Reputation, SLA, Subjective logic Cloud computing has been recognised as an important new paradigm to support small and medium size businesses and general IT applications. The advantages of Cloud computing are multifold including better use and sharing of IT resources, unlimited scalability and flexibility, high level of automation, reduction of computer and software costs, and access to several services. However, despite the advantages and rapid growth of Cloud computing, it brings several security, privacy and trust issues that need immediate action. Trust is an important concept for cloud computing given the need for consumers in the cloud to select cost effective, trustworthy, and less risky services [2] . The issue of trust is also important for service providers to decide on the infrastructure provider that can comply with their needs, and to verify if the infrastructure providers maintain their agreements during service deployment. The work presented in this paper is being developed under the FP7 EU-funded project called OPTIMIS [5] [13] to support organisations to externalise services and applications to trustworthy cloud providers. More specifically, the project focuses on service and infrastructure providers. One of the main goals of OPTIMIS is to develop a toolkit to assist cloud service providers to supply optimised services based on four different aspects, namely trust, risk, eco-efficiency, and cost. As part of the overall goal in OPTIMIS, this paper, describes a trust model to support service providers (SP)
This paper proposes a broker architecture that enables the gathering of security related events of the cloud service providers, which otherwise is difficult to be shared with the end users, and uses the reputation model proposed in REF to build the security reputation of the cloud service providers.
Trust Model for Optimized Cloud Services
IFIPTM
Computer Science