Secure Escrow and Settlement Architecture for High-Value Web3 Marketing Campaigns: Multi-Sig, Role Segregation, and Formal State Transition Controls

Abstract

Escrow trust is a foundational requirement for high-value campaign execution in Web3 marketing marketplaces. When campaign budgets exceed USD 50,000 and settlement is enforced on-chain, the security properties of the escrow contract and its surrounding settlement architecture determine whether the platform can be trusted by enterprise brands. Naive escrow designs — single-key deployment, monolithic contract logic, and implicit state transitions — expose platforms to fund loss through key compromise, smart contract exploit, and fraudulent dispute resolution. This paper presents SESA (Secure Escrow and Settlement Architecture), a formal engineering framework for Web3 campaign escrow that integrates multi-signature approval policies, strict role segregation between campaign management and fund release authority, control-plane and data-plane separation with hardware-backed signing, and explicit finite-state machine governance of all escrow lifecycle transitions including dispute resolution. SESA is grounded in a formal threat model that enumerates eleven attack vectors specific to Web3 escrow systems and maps each to a corresponding architectural control. A formal verification of the escrow state machine using the TLA+ specification language demonstrates the absence of deadlock, fund loss, and unauthorised release under all reachable states. A gas cost analysis of the reference Solidity implementation demonstrates that SESA's security controls add a mean overhead of 23% in gas cost relative to a naive single-key escrow — a trade-off that enterprise buyers consistently accept in exchange for verifiable security assurances. SESA enables campaign budgets that would be commercially unviable under insecure escrow designs to flow safely through the platform, directly expanding the addressable market for high-value brand partnerships.