*Article* **EconLedger: A Proof-of-ENF Consensus Based Lightweight Distributed Ledger for IoVT Networks**

**Ronghua Xu, Deeraj Nagothu and Yu Chen \***

> Department of Electrical and Computer Engineering, Binghamton University, SUNY, Binghamton, NY 13905, USA; rxu22@binghamton.edu (R.X.); dnagoth1@binghamton.edu (D.N.)

**\*** Correspondence: ychen@binghamton.edu; Tel.: +1-607-777-6133

**Abstract:** The rapid advancement in artificial intelligence (AI) and wide deployment of Internet of Video Things (IoVT) enable situation awareness (SAW). The robustness and security of IoVT systems are essential for a sustainable urban environment. While blockchain technology has shown grea<sup>t</sup> potential in enabling trust-free and decentralized security mechanisms, directly embedding cryptocurrency oriented blockchain schemes into resource-constrained Internet of Video Things (IoVT) networks at the edge is not feasible. By leveraging Electrical Network Frequency (ENF) signals extracted from multimedia recordings as region-of-recording proofs, this paper proposes EconLedger, an ENF-based consensus mechanism that enables secure and lightweight distributed ledgers for small-scale IoVT edge networks. The proposed consensus mechanism relies on a novel Proof-of-ENF (PoENF) algorithm where a validator is qualified to generate a new block if and only if a proper ENF-containing multimedia signal proof is produced within the current round. The decentralized database (DDB) is adopted in order to guarantee efficiency and resilience of raw ENF proofs on the off-chain storage. A proof-of-concept prototype is developed and tested in a physical IoVT network environment. The experimental results validated the feasibility of the proposed EconLedger to provide a trust-free and partially decentralized security infrastructure for IoVT edge networks.

**Keywords:** electrical network frequency (ENF); Proof-of-ENF (PoENF); consensus; blockchain; security; Internet of Video Things (IoVT)
