A Blockchain‐Based Attribute‐Based Conditional Proxy Re‐Encryption Scheme

ABSTRACT To address the challenges of coarse‐grained access control, collusion attack risks, and massive data storage issues in cross‐departmental traffic data sharing within Intelligent Transportation Systems (ITS) scenarios, this study proposes an Attribute‐Based Conditional Proxy Re‐Encryption (AB‐CPRE) scheme integrated with blockchain technology. This scheme employs a conditional proxy re‐encryption mechanism to achieve fine‐grained access control based on device attributes and access policies, thereby defending against collusion attacks by proxy nodes and malicious users. By combining the distributed ledger of blockchain and IPFS's distributed storage of IPFS, a verifiable system is constructed that includes ciphertext hashes, a complete set of device attributes, and operational conditions. This ensures data integrity while reducing the computational and storage pressure on edge servers. Security analysis demonstrates that the scheme satisfies adaptive IND‐CCA security under the standard model, and performance evaluation indicates significant improvements in computational efficiency and communication overhead compared with similar schemes.