A Research On Time-bound Hierarchical Access Control In Cloud Computing

With the development of cloud computing, data providers tend to outsource their local data to the cloud. However, data outsource to the cloud will bring some security problems, because data providers want their data secure to the cloud service provider. Moreover, data provisers want users to access data on cloud according to their permissions. Hence, the research on data access control in cloud computing become an important issue. Recently, Chen et al. first proposed a hierarchical access control scheme in cloud computing, however, they did not consider the time-bound property. In some applications(e.g., Pay-TV system), time-bound property is very necessary, because a user may subscribe some data in cloud in a period of time(e.g. a week, a month or a few months).In this thesis, we propose two schemes to solve the time-bound hierarchical access control in cloud computing. The first scheme is suitable for continuous time, and in the same security level, user key generated in this scheme is shorter than the recently proposed schemes. Moreover, the key generation phase for mobile clients is acceptable. No tamper-resistant device is needed in our first scheme, which make it more widely used in security area. The second scheme is suitable for discrete time and the applicability of this scheme is more widly than the first scheme in time-bound property. Moreover, the key generation phase of the second scheme is also efficient.Finally, we implement the first scheme by using the HDFS(Hadoop File System). We design a prototype about hierarchical access control system in the cloud. According to the experimental results, the execution time of encryption and decryption in our system are acceptable.