Dynamic Keyword Search With Hierarchical Attributes in Cloud Computing

A growing number of organizations and individuals outsource their data to the cloud. As the cloud service provider is potentially untrustworthy, cloud user needs to encrypt their sensitive data before outsourcing. One challenge of the cloud service is how to provide an effective search on encrypted data while preserving user privacy. The existing attribute-based keyword search (ABKS) scheme has addressed this issue and enabled a data owner to conduct the search over the outsourced data utilizing an access policy. However, the encryption cost in ABKS linearly increases with the number of attributes in the access policy. In this paper, we proposed a dynamic hierarchical ABKS (DHABKS) scheme to efficiently achieve fine-grained search authorization. We introduced the attribute hierarchy into access policy to improve the encryption performance of the scheme and devised a dynamic updating access policy to largely reduce the workload of the data owner. The efficiency and effectiveness of the DHABKS scheme are validated by extensive experiments using real data sets.