Resource-Aware Lightweight Security Architecture for Hybrid PoE–PoC Blockchain Consensus: Adaptive Security Level Control and Priority Queue Management

Abstract

Resource-constrained blockchain deployments in Internet-of-Things (IoT), smart grid, and edge computing environments demand consensus protocols that minimise CPU cycles, memory footprint, energy consumption, and bandwidth usage (Objective 3) while preserving meaningful security protection with bounded verification overhead (Objective 4). Existing consensus mechanisms either impose fixed maximum security overhead regardless of threat level—wasting resources during benign operation—or sacrifice security to achieve resource efficiency. This paper presents two lightweight security components of the Hybrid Proof-of-Effort and Proof-of-Credibility (HPoC-PoE) consensus algorithm that jointly address Objectives 3 and 4: (i) Adaptive Security Level Control, a four-level verification intensity framework (security-level 0–3) with dual-trigger adaptation—queue-pressure escalation (pending-txs > pending-alert-threshold = 1500) and stability-based de-escalation (security-stable-required = 5 stable cycles)—supported by a parameterised verify-tx-secure() function and the run-security-sweep() evaluation procedure; and (ii) Resource-Aware Priority Queue Management, an honest-first queue trimming algorithm (trim-pending-queue()) that enforces a configurable pending-capacity = 2000 bound while preferentially preserving legitimate transactions, combined with a batch-size = 50 limit preventing CPU saturation per consensus round. Both mechanisms are implemented in NetLogo 6.4.0 and evaluated across 20–100 nodes over 200-tick simulations with 10 independent repetitions. Key results: average security overhead of 1.14 per tick at level 1 (43% below anomaly threshold θ = 2.0); 38% overhead reduction at level 0 vs level 3; honest throughput degradation reduced from 27.4% to 4.5% under DoS flooding with queue management; and Pareto-optimal security-performance balance across all four levels validated by OLS regression (κ = 0.097, R² = 0.97). Comparative analysis confirms HPoC-PoE is the only evaluated consensus mechanism providing both adaptive security level control and automated priority queue management within a unified lightweight framework.