Fog-Blockchain Frameworks for Smart Urban Surveillance

Abstract

The rapid urbanization witnessed globally has precipitated a surge in demand for intelligent, real‑time surveillance systems capable of ensuring public safety, optimizing traffic management, and supporting emergency response. Conventional cloud‑centric surveillance architectures, although providing centralized data management, often incur significant communication delays, high network bandwidth consumption, and present single points of failure that can be exploited by malicious actors. Moreover, the volume of high‑definition video streams generated by myriad cameras across a city places an onerous load on backbone networks and centralized data centers. Fog computing offers a compelling solution by decentralizing computation and storage to intermediary nodes—located closer to data sources—thereby mitigating latency, reducing bandwidth use, and enabling preliminary data analytics at the network edge. However, fog environments introduce new security and trust challenges: edge nodes may be hosted in untrusted settings, lack robust tamper‑resistant hardware, and face insider threats that could undermine data integrity.

Blockchain technology, with its distributed ledger model and consensus protocols, presents an opportunity to bolster trust among geographically dispersed fog nodes without relying on a central authority. By recording immutable hashes of processed surveillance metadata and enforcing access policies through smart contracts, a Fog‑Blockchain integration can guarantee provenance, detect tampering, and enable transparent audit trails for all stakeholders. In this manuscript, we propose a comprehensive Fog‑Blockchain framework tailored to smart urban surveillance. The framework delineates a three‑tier architecture—comprising IoT sensor devices, fog nodes, and a consortium blockchain network—alongside a detailed data flow pipeline for video preprocessing, metadata extraction, ledger commit, and integrity verification.

We implement a prototype using off‑the‑shelf edge hardware (Raspberry Pi 4B units and commodity servers), Hyperledger Fabric for the blockchain layer, and lightweight machine‑learning models for object detection at the fog tier. Performance is evaluated through metrics such as end‑to‑end latency, transaction throughput, integrity verification time, and resilience under node failure scenarios. Results indicate that embedding blockchain within fog networks reduces average latency by up to 45% compared to cloud‑only solutions while maintaining a high transaction throughput (65 TX/s) and enabling integrity audits in under 100 ms. The system sustains operations with up to 40% of fog nodes offline, demonstrating robust fault tolerance.