How to secure outsourcing data in cloud computing is a challenging problem, since a cloud environment cannot been considered to be trusted. The situation becomes even more challenging when outsourced data sources in a cloud environment are managed by multiple outsourcers who hold different access rights. In this paper, we introduce an efficient and novel tree-based key management scheme that allows a data source to be accessed by multiple parties who hold different rights. We ensure that the database remains secure, while some selected data sources can be securely shared with other authorized parties.
Zhou, M., Mu, Y., Susilo, W., Yan, J. & Dong, L. (2012). Privacy enhanced data outsourcing in the cloud. Journal of Network and Computer Applications, 35 (4), 1367-1373.