中文摘要：

随着云计算规模化和集约化的发展,云安全问题成为云计算领域亟待突破的重要问题.访问控制技术是安全问题的重中之重,其任务是通过限制用户对数据信息的访问能力及范围,保证信息资源不被非法使用和访问.主要对目前云计算环境下的访问控制问题进行研究,首先介绍访问控制理论;然后分析了云计算环境下的访问控制技术体系框架,重点从云计算访问控制模型、基于ABE（attribute-based encryption）密码体制的云计算访问控制、云中多租户及虚拟化访问控制这3个方面对云计算环境下的访问控制问题进行综述,并且调研了工业界云服务提供商和开源云平台的访问控制机制;最后对未来的研究趋势进行了展望.

英文摘要：

With the intensive and large scale development of cloud computing, security becomes one of the most important problems. As an important part of security domain, access control technique is used to limit users＇ capability and scope to access data and ensure the information resources not to be used and accessed illegally. This paper focuses on the state-of-the-art research of access control technology in cloud computing environment. First, it briefly introduces access control theory, and discusses the access control framework in cloud computing environment. Then, it thoroughly surveys the access control problems in cloud computing environment from three aspects including cloud access control model, cloud access control based on ABE （attribute-based encryption） cryptosystem, and multi-tenant and virtualization access control in cloud. In addition, it probes the best current practices of access control technologies within the major cloud service providers and open source cloud platforms. Finally, it summarizes the problems in the current research and prospects the development of future research.