Certificateless public key encryption with equality test

In this paper, we present the concept of certificateless public key encryption with equality test (CL-PKEET), which integrates certificateless public key cryptography (CL-PKC) into public key encryption with equality test (PKEET) to solve the key escrow problem of identity-based encryption with equality test (IBEET). In the CL-PKEET scheme, the receiver first computes his private key with the receiver's secret value and the partial private key generated by the key generation center (KGC). The trapdoor is generated with this private key. Then, using the trapdoor, the receiver authorizes the cloud server to test the equivalence between his ciphertexts and others' ciphertexts. We formalize the system model and definition of CL-PKEET, propose the security models by considering four types of adversaries, and then present a concrete CL-PKEET scheme. Our proposal achieves the IND-CCA security against adversaries without trapdoor, and the OW-CCA security against adversaries with trapdoor. Furthermore, compared with IBEET and PKEET, our proposal which has the features of CL-PKC solves certificate management and key escrow problems simultaneously.