A402: Bridging Web 3.0 Payments and Web 2.0 Services with Atomic Service Channels

2026-03-01

AI Summary

Existing x402 standards fail to achieve end-to-end atomicity between service execution, payment, and delivery in Web 2.0 environments, hindering trustworthy machine-to-machine (M2M) commerce by autonomous AI agents. This work proposes the A402 architecture, introducing the Atomic Service Channel (ASC) protocol that embeds Web 2.0 services into Web 3.0 payment channels. By leveraging a TEE-assisted adapter signature, a privacy-preserving liquidity vault, and off-chain service channels, ASC enforces atomic binding between service provision and payment settlement. The design ensures strong consistency and privacy under high-frequency micropayments, supports dual integration with Bitcoin and Ethereum blockchains, and achieves several orders of magnitude improvement over x402 in both performance and on-chain cost, all while providing security guarantees under minimal trust assumptions.

Technology Category

• Multiagent Systems: Mechanism Design
• Cognitive Modeling & Cognitive Systems: Agent Architectures
• Machine Learning: Hardware-aware ML

Application Category

• Security and Privacy: Blockchains and distributed ledgers
• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Responsible Web: Machine-in-the-loop, human agency and autonomy

Abstract

The rapid proliferation of autonomous AI agents is driving a shift toward Machine-to-Machine (M2M) commerce, where software agents are expected to autonomously invoke and pay for Web 2.0 services. While Web 3.0 payments offer a programmable foundation for such interactions, the recently proposed x402 standard fails to enforce end-to-end atomicity across service execution, payment, and result delivery. In this paper, we present A402, a trust-minimized payment architecture that securely binds Web 3.0 payments to Web 2.0 services. A402 introduces Atomic Service Channels (ASCs), a new channel protocol that integrates service execution into payment channels, enabling real-time, high-frequency micropayments for M2M commerce. Within each ASC, A402 employs an atomic exchange protocol based on TEE-assisted adaptor signatures, ensuring that payments are finalized if and only if the requested service is correctly executed and the corresponding result is delivered. To further ensure privacy, A402 incorporates a TEE-based Liquidity Vault that privately manages the lifecycle of ASCs and aggregates their settlements into a single on-chain transaction, revealing only aggregated balances. We implement A402 and evaluate it against x402 with integrations on both Bitcoin and Ethereum. Our results show that A402 delivers orders-of-magnitude performance and on-chain cost improvements over x402 while providing trust-minimized security guarantees.

Problem

• M2M commerce
• Web 3.0 payments
• Web 2.0 services
• atomicity
• payment-service binding

Innovation

• Atomic Service Channels
• TEE-assisted adaptor signatures
• M2M commerce
• trust-minimized payments
• Liquidity Vault