Abstract: In order to facilitate the management of resources in the cloud,the cloud computing environment is usually divided into logically independent security management domains,but there is a hidden danger in the loss of resources' physical boundary protection.Access control is one of the key technologies to solve this security problem.Aiming at the characteristic of multiple domains of cloud computing environment,this paper proposes an access control model (CT-ABAC) based on dynamic user trust to reduce the impact of malicious recommendations in the security domain and reduce the number of malicious users' visits.In the CT-ABAC model,an access request consists of subject attributes,object attributes,permission attributes,environment attributes,and user trust attributes.A dynamic fine-grained authorization mechanism is used to deny or allow this access based on the user'saccess request attribute set.At the same time,this model extends the attribute of user trust,and considers the impact of time,similarity between security domains,and penalty mechanisms on this attribute.Simulation results show that the proposed model can effectively reduce the malicious access of users and improve the success rate of trusted users.

Key words: Access control, Attribute, Cloud computing, Muti-domain, Trust