Hybrid Lightweight Proxy Re-Encryption Scheme for Secure Fog-to-Things Environment

Fog computing is a promising paradigm that can mitigate the heavy burden on cloud-central processing of the vast amount of IoT data. Although fog computing has the advantages of low latency, storage, and computing resources that serve IoT applications and things, it hardly suffers from security and privacy challenges. Proxy re-encryption (PRE) is an effective cryptographic solution to ensure the security of fog-to-things communication. However, in PRE schemes, the problem of a processing delay caused by offloading significant computational load to the proxy for re-encryption, and the heavy computation operations of data owner encryption and user decryption due to asymmetric cryptographic use, are still unresolved in the literature. In this paper, we propose a hybrid proxy re-encryption scheme that combines lightweight symmetric and asymmetric encryption algorithms to establish secure communications in fog-to-things computing. In the proposed scheme, the computational cost incurred by fog nodes to carry out the re-encryption process is highly efficient. Meanwhile, the scheme can reduce the encryption and decryption overheads for end-users with resource-constrained devices. Security and performance analyses are conducted, and the results indicate that our scheme is secure, highly efficient, and lightweight.