Security analysis of public key encryption with filtered equality test

Public key encryption with equality test can provide a very simple add-on in which any one can directly perform testing over a pair of ciphertexts to check whether the underlying messages are identical or not without decryption. To restrict the such test power for different scenarios, that of delegated equality test is introduced to allow only the authenticated party to perform the test. In this paper, we focus on the security of public key encryption with filtered equality test (PKE-FET). The delegation to the party is only of a message set for designated testers in PKE-FET, which implies it cannot test any underlying message out of the set. We aim for investigating distinct security notions (static and adaptive security) with specific properties of the potential adversaries. Finally, we show the relationship between the security and complexity, and show the scheme of Huang et al. can reach adaptive security.