Proof of Contribution (POC): A Contribution-Backed Consensus Mechanism Anchored to Verifiable Economic Value

Mainstream blockchain consensus mechanisms exhibit a structural security gap: consensus power is weakly coupled to verifiable economic value creation, allowing capital accumulation, short-window manipulation, and governance capture to translate into long-lived influence. This paper proposes Proof of Contribution (POC), a contribution-anchored consensus weighting mechanism that binds consensus power to auditable, reproducible C/S/G (Consumption / Supply / Growth) contribution return trajectories derived from verifiable economic value, rather than secondary-market capital. POC introduces a set of protocol-level security constraints, including a Source Axiom (only protocol-distributed contribution returns generate weight), downward-only normalization, short-cycle decay, verifiable value caps with application-local negative contributions, and epoch snapshots with delayed activation. These constraints are designed to prevent short-window manipulation, wash trading, and speculative attacks from being banked into durable consensus power, without assuming perfect cheat detection. We formalize security properties (S1–S4) under explicit assumptions and present a conditional, phase-dependent security analysis showing that, as real economic scale grows, the cost of capturing a fixed fraction of consensus power increases super-linearly. POC composes with weighted BFT protocols (e.g., Tendermint / HotStuff), where POC governs weight evolution and BFT ensures finality under classical Byzantine and partial synchrony assumptions. Auditability is enforced as a protocol-native closed loop: accounting rules are committed on-chain with timelocks, contributions are deterministically recomputable from public logs, and epoch outcomes are subject to public challenges with automatic, delayed consequences. We provide a reproducible toy simulator with ablations and an explicit composition boundary for time-varying weights. POC targets commerce-native, budget-auditable systems, rather than general-purpose computation.