Proof has launched x401, an open protocol that lets a website ask an AI agent to prove which verified person it is acting for and exactly what that person approved. The company also released an agent identity wallet and a production server based on the Model Context Protocol (MCP), which connects the system to AI assistants including Meta’s Muse, ChatGPT dots, Grok and Claude.
x401 extends HTTP 401, the web’s standard response for unauthorized requests, so a site can specify the evidence an agent must provide before proceeding. A website can request verified identity claims such as legal name, age or nationality at a required level of assurance, and can ask the consumer to cryptographically sign the terms of a specific transaction.
The agent passes the request to the consumer, who authenticates with a biometric on their own device. Proof’s wallet displays the information and transaction terms being requested, and when the consumer approves, a hardware-protected key signs the response. The website then checks the issuer, credential, signature and transaction terms, and can keep the signed evidence in case the transaction is later disputed. If an agent changes the amount, recipient or other signed terms, the signature no longer validates.
Each verified person holds an X.509 certificate issued by Proof’s WebTrust-audited certificate authority after identity proofing that meets the U.S. National Institute of Standards and Technology’s Identity Assurance Level 2. Proof says the credential belongs to the person and can be reused across relationships, with selective disclosure of specific attributes.
Websites can request basic claims, including verified age, country of residence and email, without a sales process or negotiated agreement, and can pay Proof per claim using x402, an HTTP-native payment protocol stewarded by the Linux Foundation. Proof says x401 is also designed to work with AP2 and Verifiable Intent, specifications developed by Google and Mastercard and now stewarded by the FIDO Alliance for recording what a person authorized an agent to do.
Superfluid, which runs settlement infrastructure for tokenized markets, implemented x401 in its Superfluid Wallet in September.
“Businesses are being asked to accept instructions from software acting for a customer, but they cannot reliably prove who that customer is or what the customer approved,” said Pat Kinsel, Proof’s founder and chief executive. “Blocking agents is understandable, but it’s not sustainable.”
Proof pointed to Amazon’s decision in September to block Muse from its marketplace, saying Amazon had cited concerns that the agent did not identify itself and moved through accounts and transactions without Amazon’s knowledge or consent.
Developers can deploy x401 using the protocol, identity scheme, implementation guides and a reference implementation for Cloudflare Workers, with guides for Node, Python and Go.
Sources: GlobeNewswire
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By the ID Tech Editorial Team
