Abstract: The nodes in the environment of cloud computing are allowed to connect with each other through Internet. It provides two methods to keep the security of the environment, which are the access control and the secure communications. This paper focuses on the access control. The trust model using the social trust method between people in the real world is introduced. A new method TDLAC（Trustworthy and Dynamic Level Access Control） is proposed. For building the trust model between the nodes, the best node to connect is selected by considering the ability of the management between these nodes while computing the trust values of these nodes. The result of the simulation experiments shows that the algorithm can be used into cloud environment and the validity and reliability of the system are improved by considering the ability of the management between these nodes to reduce the costs.

Key words: cloud computing, trust model, dynamic level access control

摘要： 云计算是通过Internet实现节点间的交互，目前Internet提供两种方式来保障安全机制：访问控制和安全通信。主要研究访问控制，借鉴社会学中人际关系信任模型，提出“可信”动态级访问控制（Trustworthy and Dynamic Level Access Control，TDLAC）方法，该方法建立云节点的信任机制，计算节点间的信任值的同时，还综合考虑节点的处理能力，在候选节点中选择最优节点进行交互。仿真证实，考虑节点处理能力的算法能适用于云计算环境，并能在尽可能少的成本花费下提高系统的可靠性和正确性。

关键词: 云计算, 信任模型, 动态级访问控制