Keyword search with access control over encrypted data in cloud computing

Cloud computing has become an increasingly popular service for data storage and processing. To keep users' data on the cloud from leaking to unauthorized users, probably including the cloud service providers, the data must be stored in an encrypted form. In the meantime, for data intended for sharing, an efficient access control must be provided. A common operation on the data is keyword search. Currently, search operation over encrypted search is performed at the cloud servers and access control for the in-cloud data is usually enforced by users. Separation of the two types of operations can lead to reduced efficiency and compromised privacy for users with a given set of access privileges to search over encrypted cloud data. In this paper, we study the problem of keyword search with access control over encrypted data in cloud computing. We first propose a scalable framework where user can use his attribute values and a search query to locally derive a search capability, and a file can be retrieved only when its keywords match the query and the user's attribute values can pass the policy check. Using this framework, we propose a novel scheme called KSAC. KSAC utilizes a recent cryptographic primitive called HPE to enforce fine-grained access control, perform multi-field query search, and support the derivation of the search capability. Intensive evaluations on real-world dataset are conducted to validate the applicability of the proposed scheme.