References

Normative References

[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC 8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, May 2017.
[RFC 8615] Nottingham, M., "Well-Known Uniform Resource Identifiers (URIs)", RFC 8615, May 2019.

[RFC 3161] Adams, C., et al., "Internet X.509 Public Key Infrastructure Time-Stamp Protocol (TSP)", RFC 3161, August 2001.
[RFC 7800] Jones, M., Bradley, J., and Tschofenig, H., "Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)", RFC 7800, April 2016.
[RFC 9421] Backman, A., et al., "HTTP Message Signatures", RFC 9421, February 2024.
[RFC 9457] Nottingham, M., Wilde, E., and S. Dalal, "Problem Details for HTTP APIs", RFC 9457, July 2023.
Fisher, D. and McCormack, B., "Identity, Trust, and the Legal Foundations of Agentic Commerce", March 2026.
Stripe and Tempo Labs, "Machine Payments Protocol", IETF Internet-Draft, 2026.
OpenAI and Stripe, "Agentic Commerce Protocol", v2026-01-30.
Google, "Universal Commerce Protocol", v1.0, January 2026.
Google, "Agent Payments Protocol (AP2)", v0.1, September 2025.
Google, "Agent-to-Agent Protocol (A2A)", v1.0, 2025. (Donated to Linux Foundation June 2025; v1.0 released subsequently.)
Anthropic, "Model Context Protocol", spec version 2025-11-25.
Visa, "Trusted Agent Protocol", 2025.
Mastercard and Google, "Verifiable Intent", v0.1, March 2026.
Cloudflare, "Web Bot Auth", draft-meunier-web-bot-auth-architecture, 2025.
Coinbase and Cloudflare, "x402 Protocol", 2025.
[EIP-712] Bloemen, R., Logvinov, L., and Evans, J., "Typed structured data hashing and signing", Ethereum Improvement Proposal 712.