BPS-VSS: A Blockchain-Based Publish/Subscribe Video Surveillance System with Fine Grained Access Control

In recent years, the video surveillance system has become an indispensable management tool for cities. The surveillance system can improve the effectiveness of management and supervision and reduce the possibility of crime. Video surveillance as a service is a type of cloud service that can reduce redundant information and communications technology (ICT) facilities. Users use video surveillance services through a publish/subscribe (P/S) model. In this paper, we propose a blockchain-based publish/subscribe video surveillance system with fine grained access control. A P/S service model for the video surveillance is given and the matching efficiency is improved using a multi-level index mechanism. Ciphertext-policy attribute-based encryption (CP-ABE) is adopted to encrypt the access control policy for a published video surveillance, and only the subscriber with satisfied attributes can decrypt and subscribe video services. In traditional CP-ABE schemes, access policy is stored and granted by the cloud, which lacks credibility due to centralization. We use blockchain to record the access policy, realizing user self certification. The video received from the camera is encrypted and stored in InterPlanetary File System (IPFS) node connected to the blockchain network. The decrypted key of the video is encrypted by CP-ABE. Finally, the access policy, decrypted key, video metadata, the hash value returned by IPFS are recorded in the blockchain.