A Batch Identity-Based Encryption Scheme for Object-Level Authorization of Smart Tourism Data

When smart tourism data are shared across scenic areas, hotels, transportation platforms, and regulatory authorities, existing access control schemes often struggle to simultaneously support batch authorization for data object sets, multi-authority collaboration, revocation-version binding, and low-latency online encryption. To address these challenges, this paper proposes a Threshold Distributed Batch Identity-Based Encryption scheme for object-level authorization of smart tourism data, termed TD-BIBE. The scheme jointly binds data object identities, batch labels, authorization periods, revocation versions, and authorization contexts to ciphertext access control. It employs Shamir secret sharing for threshold distributed key generation, preventing any single authorization authority from obtaining the complete master secret key. Set-polynomial digests and membership witnesses are used to support batch authorization over identity sets and object-level membership verification. A revocation-version binding mechanism restricts the validity scope of authorization materials, while an offline/online encryption structure reduces the online computational overhead of data providers. Formal security analyses are conducted in the random oracle model with respect to data confidentiality, object-level authorization, batch-label binding, revocation-version binding, resistance to unauthorized key-combination attacks, and threshold authorization security. Experimental results demonstrate that TD-BIBE is suitable for cross-departmental, multi-object, and on-demand data sharing in smart tourism scenarios.