Blockbond Hardening: Securing Pooled-Hash Protocols Against Traffic Tampering, MITM Hash-Rate Hijacking, and Template Coercion

Pooled proof-of-work ecosystems inherit an expanding attack surface from plaintext or weakly authenticated transport, centralized job selection, and latency-sensitive job propagation, enabling adversaries to siphon hash power, manipulate workloads, or degrade availability at scale. This paper systematizes threats against mining coordination protocols, including man-in-the-middle share redirection, extranonce/job injection, and routing-layer disruption that silently wastes miner effort, then maps each vector to concrete transport- and protocol-layer countermeasures such as AEAD-secured sessions, authenticated key agreement, header-only job separation to curb emptyblock incentives, and decentralized template declaration to resist transaction-level coercion. A practitioner-focused implementation pathway demonstrates secure role composition with a pool service, translation proxy, template provider, and negotiator, hardening legacy endpoints while progressively enabling encrypted binary framing, version rolling controls, and minerdriven template workflows. The result is a defense-in-depth blueprint that both mitigates known Stratum-era attacks and reduces single points of failure in pooled mining, providing actionable guidance for secure-by-default deployment of nextgeneration coordination under adversarial network conditions.