ZK-PPR-ABE: A Zero-Knowledge Privacy-Preserving Data Sharing Scheme

Ciphertext-policy attribute-based encryption (CP-ABE) is a suitable cryptographic technique for fine-grained data sharing in the Internet of Vehicles (IoV). However, in a highly dynamic IoV environment, existing revocable attribute-based encryption (ABE) schemes face two major challenges: ciphertext re-encryption during user revocation results in high system overhead, while identity exposure during permission verification may lead to location-privacy leakage. To address these issues, this paper proposes a privacy-preserving revocable ABE scheme based on zero-knowledge proof (ZK-PPR-ABE). First, a Merkle hash tree (MHT) is used to separate the revocation status from the ciphertext. Each revocation updates the hashes along the affected MHT path and publishes a path-update package containing the changed node hashes, while the cloud ciphertext remains unchanged. Second, the scheme combines Paillier ciphertext re-randomization with zero-knowledge succinct non-interactive arguments of knowledge (zk-SNARKs) in a blind decryption protocol to reduce the exposure of user credentials and request information during revocation verification. The security analysis establishes selective indistinguishability under chosen-plaintext attack (selective IND-CPA), collusion resistance, and request privacy under the defined indistinguishability-of-requests (IND-REQ) model. Experiments show that the scheme provides efficient revocation and scalable ciphertext storage for large-scale IoV scenarios.