Pairing-free Proxy Re-Encryption scheme with Equality Test for data security of IoT

The construction of IoT cloud platform brings great convenience to the storage of massive IoT node data. To ensure security of data collected by the IoT nodes, the data must be encrypted when the nodes upload it. However, it arises some challenge problems, such as efficient retrieval on encrypted data, secure de-duplication and massive data recovery. Proxy Re-Encryption with Equality Test (PREET) can be used to solve these problems. But, existing PREET schemes are based on bilinear pairings, which have low operational efficiency. In order to improve the overall operational efficiency, this paper constructs a Pairing-Free PREET scheme (PF-PREET). Security of this scheme is guaranteed by the Gap Computational Diffie–Hellman assumption in random oracle model. It is demonstrated that the PF-PREET scheme can achieve ciphertext indistinguishability for malicious users and one-wayness for malicious servers. It still has the same security level compared to existing PREET schemes by expanding the scope of the equality test. We discussed the efficiency of the proposed PF-PREET scheme in terms of overall running time, average running time of each phase and time overhead of tag test. The simulated experiment shows a certain improvement compared to PREET schemes using bilinear pairing.