EPF-CLPA: An Efficient Pairing-Free Certificateless Public Auditing for Cloud-based CPS

Cloud based cyber physical system (CPS) enables individuals to store and share data collected from both cyberspace and the physical world. This leads to the proliferation of massive data at a user's local site. Since local storage systems can't store and maintain huge data, it is a wise and practical way to outsource such huge data to the cloud. Cloud storage provides scalable storage space to manage data economically and flexibly. However, the integrity of outsourced data is a critical challenge because user's lose control of their data once it's transferred to cloud servers. Several auditing schemes have been put forward based on public key infrastructure (PKI) or identity-based cryptography to verify data integrity. However, “the PKI-based schemes suffer from certificate management problem and identity-based schemes face the key escrow” problem. Therefore, to address these problems, certificateless public auditing schemes have been introduced on the basis of bilinear pairing, which incur high computation overhead, and thus it is not suitable for CPS. To reduce the computation overhead, in this paper, Using elliptic curve cryptography, we propose an efficient pairing-free certificateless public auditing scheme for cloud-based CPS. The proposed scheme is more secure against type I/II/III adversaries and efficient compared to other certificateless based schemes.