PKE-ET-HS: Public Key Encryption with Equality Test for Heterogeneous Systems in IoT

With the continuous development of the Internet of Things (IoT), a growing number of users choose to store the data collected from their smart devices on a cloud server for saving costs. However, the security and privacy issues that accompany the cloud-assisted IoT are also becoming increasingly apparent. Considering the untrusted nature of the cloud server, the data accumulated by the smart sensor must be encrypted before outsourcing to the cloud server. Nevertheless, the above mechanism raises another serious problem. For users of another public key cryptosystem, it is impractical to download all the data stored in the cloud to find the data he needs. To solve this problem, we first, proposed a public key encryption with equality test for heterogeneous systems (PKE-ET-HS) which combines the ideas of identity-based encryption with outsourced equality test and public key encryption with equality test. This scheme allows the authorized cloud server to retrieve whether two encryptions encrypted in a heterogeneous system contain equivalent messages. In addition, in the random oracle, the security of the proposed scheme has been given under the bilinear Diffie–Hellman assumption and the computational Diffie–Hellman assumption. Finally, storage size, computation complexity, and properties are compared with other related works. The results show that the PKE-ET-HS scheme proposed in this paper has a good performance.