Efficient Attribute-Based Searchable Proxy Re-Encryption with Policy Hiding over IoT Data

Due to the integration of cloud computing in Internet of Things (IoT) systems, an increasing volume of IoT data is encrypted and uploaded to cloud servers. Attribute-Based Keyword Search (ABKS) schemes enable authorized users to access the encrypted IoT data, however, existing schemes suffer from sensitive information exposure (caused by publicly visible access policies) and low efficiency in dynamic multi-party sharing. To alleviate these issues, this paper develops an efficient attribute-based searchable proxy re-encryption scheme with policy hiding for IoT data sharing. Specifically, the scheme employs a layered encryption architecture where symmetric encryption (e.g., AES) protects massive IoT data, and Attribute-Based Encryption (ABE) secures the symmetric key. Such design ensures that policy updates for dynamic multi-party sharing are implemented by updating the ABE ciphertext using proxy re-encryption keys, eliminating the need to re-encrypt bulk IoT data. Meanwhile, an AND-gate structure for multi-valued attributes is introduced to enforce access policies while ensuring policy hiding and protecting data owners’ sensitive information. Additionally, the proposed scheme achieves constant overhead (key/ciphertext sizes are independent of attributes), supports fast keyword search, and enables low-latency data retrieval in IoT systems. Rigorous security analysis and comparative evaluations with closely relevant schemes validate the security and practicality of our scheme.