Due to its low cost, robustness, flexibility and ubiquitous nature, cloud computing is changing the
way entities manage their data. However, various privacy concerns arise whenever potentially sensi-
tive data is outsourced to the cloud.
This paper presents a novel approach for coping with such privacy concerns. The proposed
scheme prevents the cloud server from learning any possibly sensitive plaintext in the outsourced
databases. It also allows the database owner to delegate users to conducting content-level fine-grained
private search and decryption. Moreover, our scheme supports private querying whereby neither the
database owner nor the cloud server learns query details. Additional requirement that user’s input be
authorized by CA can also be supported.