Cryptanalysis of a Transaction Scheme With Certificateless Cryptographic Primitives for IoT-Based Mobile Payments

Very recently, Qiao et al. (2021) constructed an efficient certificateless signature (CLS) scheme, and further used it as the underlying scheme to design a transaction scheme for IoT-based mobile payments. Their CLS scheme is claimed to be secure against Type I and II attackers. Unfortunately, in this article, we provide an attack method to demonstrate that their CLS scheme is insecure against Type II attackers. Furthermore, we present an improved CLS scheme to enhance the security of their scheme.