Identity based encryption with equality test

Abstract

In this research work, we propose a notion of identity-based encryption scheme with equality Test (IBE-ET). This scheme allows authorized users to test the equivalence between two messages whereby the messages are encrypted using different previously known identities. Most existing IBE-ET researches only allows checking whether two ciphertexts encrypted under same identities contain the same message. IBE-ET has many interesting applications in constructing searchable encryption and partitioning encrypted data. However, the original IBE-ET schemes lack an authorization mechanism for a user to control the comparison of its ciphertexts with others. In this research, we propose the authorization mechanism for IBE-ET. We give the definitions of the policies and propose an IBE-ET scheme supporting these two types of authorization at the same time. Our scheme supports authorization such that receiver authorizes the tester to be able to perform equality test on all of receivers' ciphertexts. The receiver gives the tester authorization corresponding to a specific ciphertext then the tester only acquires the equality test on that particular ciphertext. The tester without decryption can verify the equality between two ciphertexts after he or she receives two authorizations.