Abstract
Cloud computing has emerged as the most dominant computational paradigm in recent times. There are tremendous benefits for enterprises adopting cloud technologies. It provides resources and services on demand, pay-as-you go basis. This includes infrastructure, platform and software services. But there are still a number of security threats and challenges associated with utilizing cloud computing. A proper access control is the fundamental security requirement in any cloud environment, to avoid unauthorized access to the cloud systems. As cloud computing supports multi-tenancy and has a various categories of users with different sets of security requirements, traditional access control models and policies cannot be used. This paper discusses on various access control models used for cloud environment and presents a detailed requirement analysis for developing an access control, specifically for the cloud. A comprehensive study on various security problems associated with outsourced data on the cloud and their existing solutions are also described, with the future research directions.