ZkPSLB: Zero-Knowledge Proof-Empowered End-to-End Secured Lightweight Blockchain Framework For Smart Cities

Recently, developing technologies for smart cities, although scalable and cost-effective, have been challenging to provide anonymous verification and on-chain integrity with low overhead due to the increasing attack surface. We propose ZkPSLB, a layered end-to-end security framework to address the problem. ZkPSLB utilizes a Zero-Knowledge Concise Non-Interactive Knowledge Argument (zk-SNARK), a type of Zero-Knowledge Proof (ZKP) scheme, embedded within the Constrained Application Protocol (CoAP) for anonymous device authentication. Sensor payloads are encrypted with elliptic curve cryptography (ECC) and stored in a decentralized cloud storage system (IPFS). IPFS CIDs are committed to the chain, ensuring both off-chain confidentiality and on-chain integrity. In the evaluation conducted with 500 devices/5000 metadata, the authentication communication overhead was measured at 1952 bits. The event-based smart contract (EBSC) reduces on-chain payload and gas growth compared to storage-based designs, and its cost advantage has been validated.