EMK-ABSE: Efficient Multikeyword Attribute-Based Searchable Encryption Scheme Through Cloud-Edge Coordination

Cloud storage and edge computing provide the possibility to address the tremendous storage and computing pressure caused by the explosive growth of traffic at the edge of the networks. In this scene, as data is outsourced to the cloud or edge servers, data privacy can be leaked. For enhancing security and privacy, attribute-based searchable encryption (ABSE), as an effective technical approach, achieves controllable search of ciphertext. Aiming at addressing the issues of the low search efficiency in a single-keyword ABSE scheme and the large computing overhead of the existing multikeyword ABSE schemes, we propose a novel multikeyword ABSE scheme (EMK-ABSE) through cloud-edge coordination. The huge amounts of encrypted data is stored to cloud server (CS), while the corresponding encrypted index is uploaded to the nearest edge node (EN) to perform multikeyword search and assisted decryption. To further release the computational burden of clients, a hybrid online/offline mechanism is adopted in encryption. Security analysis indicates that the multikeyword index in EMK-ABSE has secure indistinguishability under chosen keyword attack (IND-CKA). The comprehensive evaluation proves that EMK-ABSE achieves not only encrypted multikeyword retrieval but also fine-grained access control, with lower computation complexity in the three stages of encryption, trapdoor generation, and decryption. We show that the proposed scheme has higher efficiency and practicability than the selected relative works.