BCPA: A Blockchain-Based Cross-Domain Privacy-Preserving Authentication Scheme in Internet of Things Environments

The rapid development of the Internet of Things (IoT) has driven the demand for cross-domain access and data sharing. Existing authentication schemes face various challenges in addressing complex security threats. On the one hand, multi-factor authentication independently verifies each factor, lacking deep integration and failing to establish synergistic defense mechanisms. On the other hand, cross-domain authentication requires data consistency, while traditional centralized schemes are prone to privacy leakage and single points of failure. In addition, the limited computational efficiency of resource-constrained devices and post-authentication communication further restrict the applicability of current schemes. To address the above issues, this paper proposes a Blockchain-based Cross-domain Privacy-preserving Authentication scheme (BCPA). BCPA adopts fuzzy commitment technology to fuse users biometric features with device characteristics, enabling three-factor authentication. While preserving user privacy, it records pseudonym verification information on the blockchain to ensure cross-domain data consistency. It leverages elliptic curve cryptography to achieve anonymous verification and supports both authentication factor updates and identity revocation. For resource-constrained devices, BCPA combines Physical Unclonable Function technology with lightweight cryptographic operations to reduce computational and communication overhead while ensuring device privacy. After authentication, a session key is generated using elliptic curve Diffie-Hellman (ECDH) to ensure secure communication. Security analysis and experimental results demonstrate that BCPA outperforms existing schemes in terms of privacy protection, security, and flexibility, offering a practical solution for cross-domain authentication and secure communication in IoT environments.