Blockchain-enhanced certificateless signature scheme in the standard model.

The Internet of Things (IoT), driven by wireless communication and other technologies, is gradually entering our lives and promoting the transformation of society from "informatization" to "intelligence". Certificateless signature (CLS) eliminates the characteristic of certificate management, making it an effective method for verifying large-scale data in the IoT environment. Nevertheless, hash functions are regarded as ideal random oracles in the security proofs of most CLS schemes, which cannot guarantee the security of CLS schemes in reality. In response to this problem, Shim devised a CLS scheme without random oracles in the standard model and declared it to be provably secure. Unfortunately, in this paper, we cryptanalyze Shim's CLS scheme and demonstrate that it is not resistant to public key replacement attacks from a Type Ⅰ attacker. Furthermore, to further improve the security of the Shim CLS scheme and avoid the single-point failure of the KGC and the signature forgery initiated, we propose a blockchain-based CLS scheme without a random oracle. Finally, we evaluate the comprehensive performance, and while maintaining the computational and communication performance of the Shim scheme, we resist both Type Ⅰ and Type Ⅱ attackers, as well as signature forgery initiated against public parameters.