2016 1st International Electrical Engineering Congress (IEEC 2016) May. 13-14, 2016 in IEP Centre, Karachi, Pakistan 1 I. INTRODUCTION Cloud computing is an emerging trend in computing and resource management. Establishing trust in cloud system is a complex and challenging problem. In cloud computing trust establishment has to be both identity and properties based due to its dynamic nature, complexity of infrastructure, automated services, application interdependencies, and diversity of stakeholders. Trust in cloud depends mainly upon two factors. One is the operational trust which deals with the operations of cloud service provider and other is automation of different mechanisms for service providers to provide trust. Trust is a complicated term to define. There is no comprehensive definition for it. It may be defined as Trust is a psychological state comprising the intention to accept vulnerability based upon positive expectations of the intentions or behavior of another [2]. Trusted computing is an emerging field in computing. The aim is to provide the users prof of the trustworthiness of computing services they are using. Its aim is to provide a root of trust to users using the computing facility [3]. The root of trust is the starting point in trust implementation from where the trust is started. Primarily there are two broader categories of trust in the cloud [4]. A) Implementation of trustworthy mechanisms and tools for Cloud providers; in order to automate the process of maintaining, managing and securing their infrastructure. B) Different methods that provide support to both cloud service providers and users in establishing trust in the operations of the infrastructure by continuous assessment of its operational trust (also known as the operational trust). Operational Trust depends on many factors like scalability, adaptability, availability, reliability and resilience etc [5]. All these properties interns depend on many overlapping factors. The primary focus of this paper is the enhancement of operational trust in cloud computing via providing security mechanisms at different layers of cloud. The notion is to provide efficient and pragmatic trust mechanisms which can cater the trust requirements for cloud computing. Rest of the paper is organized as follows: the taxonomy of cloud trust models is presented in section 2. Section 3 discusses OpenStack Cloud deployment. Section 4 presents the proposed trust model. Trust implementation at the Physical layer is presented in Section 5. Section 6 provides description about trust implementation at the Virtual layer. Application level trust mechanisms have been discussed in section 7. Section 8 focuses on the analysis of proposed model. The last section concluded the outcome of the paper. II. TAXONOMY OF CLOUD TRUST MODELS In this session taxonomy of trust model for cloud computing has been presented. Predominantly Trust models for cloud computing can be classified in five categories as shown in figure 1. A. Feedback Oriented Models Feedback trust model calculates the trust of cloud service provider by collecting feedback about the services from the existing customers of the cloud service provider [6-8]. These models aggregates feedbacks received from different cloud customers like Security, QoS etc into Feedback Modules as shown in figure 2. Then there is trust evaluation module which categorized different cloud service provider based upon the feedbacks collected from the customers. Finally there is a Service registry where the cloud service providers list is stored. In this category three models have been discussed. Hybrid Trust Model for Enhancing the Operational Trust in Cloud Computing Muhammad Faraz Hyder 1 and Muhammad Ali Ismail 2* 1,2 High Performance Computing Centre, Department of Computer & Information Systems Engineering, NED University of Engineering and Technology, Karachi, 75290, Pakistan 1 farazh@neduet.edu.pk, 2 maismail@neduet.edu.pk Abstract: This paper focuses on implementation of various trust mechanisms at different layers of cloud namely physical, virtual and application to enhance the operational trust in cloud computing. The notion is to build an efficient, light weight, pragmatic hybrid trust model for cloud computing. The model proposed in this paper is combination of Certificate and Feedback based Trust models (HCFTM). Keywords: Trust, Cloud Service, Hypervisor, OpenStack, Hybrid model