Degree Name

Doctor of Philosophy


School of Computing and Information Technology


Confidentiality can be usually achieved by conventional encryption, which hides sensitive data from unauthorised parties. In such encryption schemes, the decryption is all or nothing. Although it ensures the confidentiality of the encrypted data, it does not allow computing over files and sharing. Differing from the conventional encryption, functional encryption allows the decryption key holder to learn a function of the encrypted data and nothing else. Therefore, functional encryption makes computing over encrypted data and sharing of encrypted data in different levels possible.

In this thesis, we investigate functional encryption in terms of functionality, security, and efficiency. To ensure the constructed schemes are practical in real applications, we focus on functional encryption for practical functionalities, such as equality tests, inequality tests, and inner product evaluation, which are the major functionalities that can be applied in privacy-preserved data search and privacy-preserved data sharing. Precisely, functional encryption for equality tests and inequality tests can be applied in searchable encryption while the functional encryption for inner product evaluation can be applied to achieve levelled data sharing. These applications of functional encryption are very useful and essential in cloud computing security.