Traceable and Revocable Bilateral Access Control With Constant-Length Ciphertexts for Cloud Sharing

Cloud platforms provide scalable storage and sharing services for the vast amounts of data generated by Internet of Things (IoT) devices. Attribute-based matchmaking encryption (ABME) is regarded as a promising solution for protecting data security during storage and sharing, as it enables fine-grained, bilateral access control between data owners (DOs) and data users (DUs). However, existing ABME schemes lack effective traceability and revocation mechanisms, making it difficult to identify and isolate malicious DOs who continuously upload fraudulent data. Moreover, in existing schemes, the length of the ciphertext increases rapidly as the number of attributes grows, resulting in a significant rise in cloud storage costs. To address these challenges, we propose a traceable and revocable ABME scheme with constant-length ciphertexts, called TRC-ABME. In the TRC-ABME scheme, a traceable pseudonym is embedded into each ciphertext, enabling the system to identify malicious DOs and revoke all associated pseudonyms. To alleviate the storage burden on the cloud, the ciphertext length remains constant regardless of the number of attributes. Furthermore, online/offline encryption and outsourced decryption are adopted to improve computational efficiency. Security analysis shows that TRC-ABME achieves confidentiality and unforgeability in the standard model, and is resistant to collusion. Performance evaluation demonstrates that the TRC-ABME scheme provides stronger functionality with lower storage and computational overhead than existing ABME schemes.