Post-Quantum Signature Migration for Ethereum Blockchain: A Verification Metrics Study

This paper reports a five-scenarios migration study from classical ECDSA to post-quantum cryptography (PQC) and hybrid signature settings for Ethereum-like blockchains. Using reproducible pipeline outputs from a multi-repository toolchain, we compare baseline ECDSA, hybrid ECDSA+ML-DSA, ML-DSA throughput collapse, ML-DSA latency spike (larger blocks), and SLH-DSA computational bottleneck cases. We also include Layer 2 roll-up/data-availability (DA) scenarios at 2-second cadence. Results show that PQC migration substantially reduces key-exposure risk but introduces severe throughput and fee penalties under fixed block limits. Enlarging blocks restores throughput but increases propagation delay, storage growth, and fork/orphan risk. Hybrid deployment preserves migration compatibility but inherits significant fee pressure. We provide quantitative security, performance, network, and blockchain-health metrics. The results expose three migration regimes. First, fixed-cap PQC replacement (1 MB) results in significant throughput loss and fee inflation. Second, capacity compensation (larger blocks) can recover TPS but amplifies propagation delay and chain-growth pressure, increasing fork/orphan risk. Third, hybrid deployment provides compatibility and reduces crypto-graphic risk, but it incurs substantial overhead.