Efficient and attribute-value hiding bilateral access control for cloud-assisted IoT data sharing

Cloud-assisted data sharing is a fundamental enabling technology for large-scale Internet of Things (IoT) applications, but it introduces persistent security and efficiency challenges due to complex trust relationships, limited device resources, and sensitive attribute exposure. Although Attribute-Based Matchmaking Encryption (ABME) has been proposed to support bilateral access control, most existing schemes either leak attribute values during the matchmaking or decryption process, lack efficient revocation mechanisms, or impose substantial decryption overhead on resource-constrained receivers, which limits their practicality in cloud-assisted IoT environments. To address these issues, this paper presents a revocable ABME scheme that simultaneously supports bilateral access control, attribute-value hiding, and outsourced decryption. The proposed scheme enforces mutual authorization by requiring that both the sender’s and the receiver’s access policy be jointly satisfied, while preventing the cloud server from learning sensitive attribute values involved in the matching process. By securely delegating the majority of matchmaking and decryption computations to a semi-honest cloud server, the scheme enables ciphertext pre-filtering and partial decryption without revealing attribute semantics. Authorized receivers can then efficiently recover plaintexts with lightweight local computation. We formally prove that the proposed scheme achieves indistinguishability under chosen-plaintext attacks (IND-CPA) under the decisional modified bilinear Diffie–Hellman (MBDH) assumption. Extensive experimental evaluations demonstrate that the proposed scheme significantly reduces the decryption overhead on IoT devices while preserving strong attribute privacy and security guarantees, making it suitable for practical cloud-assisted IoT data sharing scenarios.