Preauthorization Usage Control Mechanism for CrossDomain in Cloud With the increase of information resources, resources are uploaded to different cloud services in different domains. In order to facilitate crossdomain access, it is necessary to grant access authority to the subject before crossdomain access. Therefore, it has gradually become a necessary trend to apply preauthorization access control mechanism in crossdomain. However, in this cloud service mode, preauthorization for crossdomain access still has some problems, such as illegal access to resources, high cost of attribute mapping, easy disclosure of privacy, etc. The above problems bring a series of new requirements for crossdomain access control in cloud, such as finegrained preauthorization access control, privacy protection and reducing mapping cost. In order to meet these requirements, a preauthorization usage control mechanism for attribute update in access execution (UCONpreA2) is proposed in this paper, and formally described. And then, the global attribute is divided into static attribute and dynamic attribute, and using local attributes for mapping. Our case analysis shows that the access control mechanism can meet the above series of requirements.

An Anonymous Attributebased Access Control System Supporting Access Structure Update It is quite common nowadays for clients to outsource their personal data to a cloud service provider. However, it causes some new challenges in the area of data confidentiality and access control. Attributebased encryption is a promising solution for providing confidentiality and finegrained access control in a cloudbased cryptographic system. Moreover, in some cases, to preserve the privacy of clients and data, applying hidden access structures is required. Also, a data owner should be able to update his defined access structure at any time when he is online or not. As in several realworld application scenarios like ehealth systems, the anonymity of recipients, and the possibility of updating access structures are two necessary requirements. In this paper, for the first time, we propose an attributebased access control scheme with hidden access structures enabling the cloud to update access structures on expiry dates defined by a data owner.