A new lightweight public key encryption with equality test for cloud storage

Public key encryption with equality test (PKEET) can test if two ciphertexts generated from different public keys contain the same message without decryption. In the application of cloud storage, PKEET could be used to search on encrypted data. Currently, there have been many researches about security, efficiency, and function of PKEET. After analyzing the ciphertext sizes in the existing proposals, we find that the ciphertext sizes in PKEET schemes are usually large. In this case, it will bring storage burden for the cloud server. To address the problem, in this paper, we introduce a new notion of lightweight public key encryption with equality test (L-PKEET). Then we present a concrete construction of L-PKEET. Furthermore, we demonstrate that L-PKEET can reduce ciphertext sizes efficiently. In terms of the computation cost and ciphertext size, we compare L-PKEET with related schemes which also achieve four kinds of authorization. The comparison results show that L-PKEET is more efficient in terms of encryption, decryption, and test algorithms. Regarding the adversaries with/without trapdoor, we theoretically prove that L-PKEET can meet OW-CCA security and IND-CCA security, respectively.