Efficient Identity-Based Encryption Scheme with Equality Test in Smart City

To support a sustainable development of smart city, smart grid is an indispensable part. Sensor technology in smart gird enables interactive real-time data transmission between cloud and the edge of the network. There are a number of research challenges in the design of smart grids. One of these research challenges is balancing customer privacy and the cloud-based power system's function optimization. Identity-based encryption with equality test (IBEET) scheme has recently been identified as a viable solution, in which customers can delegate a trapdoor to the power system control server and the server then searches on the encrypted data to determine whether two different ciphertexts are encryptions of the same plaintext. Unfortunately, existing schemes are inefficient and the trapdoor could be used to perform equality test on any message; thus, leakage of privacy. In this paper, we propose an efficient IBEET scheme with bilinear pairing, which reduces the need for time-consuming HashToPoint function and each trapdoor could only be used to perform the equality test on a particular keyword. We then prove the security of our scheme for one-way chosen-ciphertext security against a chosen identity (OW-ID-CCA) attack in the random oracle model (ROM). The performance evaluation of our scheme demonstrates that in comparison to the scheme of Ma (2016), our scheme achieves a reduction of 36.7 and 39.24 percent in computation costs during the encryption phase and test phase, respectively.