Privacy-Preserving Cross-Domain Authentication in Internet of Things

This chapter introduces a unified blockchain-assisted framework for secure cross-domain authorization and authentication in smart city IoT applications. The framework ensures flexible and easy resource access across different trust domains while protecting identity privacy. Specifically, the framework allows application service providers to delegate authentication to the blockchain, enabling user authentication with interoperability, auditability, and traceability. To prevent potential privacy risks due to the blockchain’s public nature, we employ techniques like threshold-based homomorphic encryption and random permutation, to effectively conceal sensitive identity attributes. Additionally, the framework incorporates a cryptographic accumulator and secure hash functions for streamlined user revocation via a global smart contract deployed on the blockchain. Security analysis confirms the framework’s security, and a proof-of-concept prototype is used to demonstrate its practicality and effectiveness.