{"slug":"a-new-protocol-tries-to-answer-whose-agent-is-this","citations":[{"url":"https://www.helpnetsecurity.com/2026/06/26/proofs-x401-establishes-an-open-protocol-for-ai-agent-identity-and-authorization/","committed_hash":"sha256:f0ee9d8deb05a43ee38a302ecf32f623c434b40999d5d7e59c0d351065d53b72","committed_hash_short":"sha256:f0ee9d8d…65d53b72","mime_type":"text/html","committed_at":"2026-07-27T16:00:17.550364+00:00","content_snapshot":"\n\n\n \n\n \n \n\n\t\n\n\t\n\tProof’s x401 establishes an open protocol for AI agent identity and authorization - Help Net Security\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\r\n\r\n \n\n\n\n\n\n\t\n\n\n\n\n\n

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Proof’s x401 establishes an open protocol for AI agent identity and authorization

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Proof has launched x401, an open, issuer-neutral protocol that lets any website or API ask for and verify the identity behind agents.

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With x401, a service can ask for the proof it requires: verified identity, age, membership, organizational affiliation, signing authority, proof of humanness, orf another trusted claim. The agent presents a compatible credential and authorization. The service verifies the issuer, claim, scope and action before proceeding.

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Identity establishes who or what an agent represents. Authorization establishes what it is permitted to do. x401 binds the two into proof and unlocks agents’ ability to act on people’s behalf.

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“AI is making actions and content effortless to generate. Trust will come from knowing who stands behind them,” said Pat Kinsel, CEO of Proof. “x401 gives every service a common way to ask for proof. Proof Digital ID gives people and organizations a high-assurance way to answer—with a signed record of who authorized what.”

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Open by design

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x401 is an open protocol allowing any conforming issuer to deliver x401-compatible credentials. Any agent can present them. Every service determines which claims, issuers and levels of assurance it will accept.

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That separation allows one protocol to support many forms of authority without forcing the internet to adopt a single identity provider or credential model.

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x401 was developed by Proof with technical contributors from leading payments, identity and AI organizations. The public specification, implementation materials, and complete contributor list are available at x401.id.

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Proof will submit x401 to the FIDO Alliance’s agentic authentication standards workgroup.

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Built to complete the agent stack

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x401 is designed to work with the protocols already emerging around agentic activity. In payments, x402 enables machines to make payments. AP2 and Verifiable Intent capture instructions and approvals in commerce. x401 now completes the missing link, when used together with these other protocols, agents can now pay, prove a person’s identity, and authorize specific actions.

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“x402 is the open standard that lets agents pay for web resources over HTTP with pay-per-request settled in stablecoins, with no accounts or API keys. Through Circle Agent Stack and USDC, which settles nearly all x402 volumes, Circle has been one of its core contributors. x401, built with Proof, pairs that with identity: x402 answers how an agent pays, x401 answers who it is. Those are the first two questions any agentic transaction has to clear, and now each has an open standard. Circle is proud to be an early adopter and co-endorser of x401,” said Gagan Mac, VP Product, Circle.

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Proof’s digital identity: A high-assurance identity that can sign

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Built on Verifiable Credentials, Proof’s digital identity is the inline implementation of OID4VC Issuance and Presentation, allowing people to verify their identity to an IAL2 standard and enroll just-in-time or instantly reauthenticate with a biometric. Developers request identity and Proof manages the complexity of who is enrolled vs not.

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Using selective disclosure and zero-knowledge proofs, someone can prove that they are verified, their nationality, over a required age or authorized to represent an organization without exposing their complete identity record.

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In addition to credential presentation, Proof’s platform supports transaction signing, producing verifiable records. The API supports signing authorizations like AP2 with Verifiable Intent and cryptographically binds a verified identity to any payment, transaction, or payload. Verifiable records prove who you are and what you’ve authorized, creating the evidence that every industry requires in the agentic era. U.S. law has recognized agreements made by electronic agents for decades. Proof provides what’s been missing: trustworthy proof of the person behind the transaction.

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Proof’s digital identity is backed by Proof’s Kantara-certified NIST IAL2 identity service and WebTrust-audited certificate-authority infrastructure. As a Certificate Authority that pairs a publicly trusted, audited certificate hierarchy with IAL2-grade identity proofing, Proof’s digital identity is the only legal credential that can secure everything a person signs, does in person, does online, or delegates to an agent.

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\n\n\n\n\n\n\n\n\n","snapshot_chars":83629,"live_check":"changed"},{"url":"https://automationtoday.net/news/proof-launches-protocol-to-verify-identities-behind-ai-agents/","committed_hash":"sha256:0687081efa56bb3546e4a624b60cea81ae593747d6557343a8b7d76f1d42b5cf","committed_hash_short":"sha256:0687081e…1d42b5cf","mime_type":"text/html","committed_at":"2026-07-27T16:00:18.269589+00:00","content_snapshot":"\n\n\n\n\t\n\t\n\t\n\t\t\n\t\n\t\t\n\t\t\n\t \nAutomation Today: Publication & Newsletter: Proof Launches Protocol to Verify Identities Behind AI Agents\n\tProof Launches Protocol to Verify Identities Behind AI Agents – Automation Today: Publication & Newsletter\n\n\t\n\t\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n \t\r\n\t\t\n\t\t\t\n\n\n\n\t\n\t\t\t
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NEWS FOR THE AI-POWERED INTELLIGENT AUTOMATION ECOSYSTEM
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Proof Launches Protocol to Verify Identities Behind AI Agents

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As AI agents become the main engine behind automation and act on behalf of unidentified humans, Boston-based Proof has launched an open protocol intended to help websites and APIs verify the identity and authority behind AI agents performing those actions.

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The protocol, called x401, enables services to request credentials confirming information such as identity, organizational affiliation, signing authority or other trusted claims before allowing an AI agent to complete an action. Proof said x401 is issuer-neutral and allows organizations to determine which identity providers and assurance levels they will accept.

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The company said x401 was developed with contributors from the payments, identity and AI sectors and will be submitted to the FIDO Alliance’s agentic authentication standards workgroup. The protocol is intended to complement emerging standards for agentic payments and digital transactions by providing a standardized approach to authorization.

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“AI is making actions and content effortless to generate. Trust will come from knowing who stands behind them,” said Pat Kinsel, founder and CEO of Proof. “x401 gives every service a common way to ask for proof. Proof Digital ID gives people and organizations a high-assurance way to answer—with a signed record of who authorized what.”

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The company said developers can begin using the protocol immediately through documentation, sample applications and integrations with AI assistants including Claude and ChatGPT.

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\"Support\"/

Agent Identity Verification: How AI Agents Authenticate Purchases in 2026

How Mastercard Agent Pay tokens, Visa Trusted Agent attestations, AP2 Verifiable Credentials, and W3C DIDs prove an AI agent is authorized to transact in 2026.

Written by Eco
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AI agents now hold payment credentials, browse merchant catalogs, and submit checkout requests on behalf of human principals. The acquirer at the other end of the transaction has a problem no card network was designed to solve: how do you tell a legitimately delegated agent from a scripted attacker reusing a stolen token? Agent identity verification is the layer that answers that question. This article maps the four production approaches shipping in 2026, the consent flow that ties them to a human, and the threat model each is built to defeat.
​

What Is Agent Identity Verification?

Agent identity verification is the cryptographic process of proving that a software agent submitting a payment is (a) a known agent registered with a network or issuer, (b) currently authorized by a specific human principal, and (c) acting within a scoped mandate. It binds agent, user, and intent into a single signed credential the merchant or acquirer can verify before settlement.
​

The 2026 landscape splits into four implementation models: tokenized agent identities (Mastercard Agent Pay), attestation headers (Visa Trusted Agent Protocol), Verifiable Credentials with signed mandates (Google's AP2), and decentralized identifiers (DIDs, used by crypto-native agents settling onchain). Each maps to a different trust anchor: card network, acquirer, issuer-signed VC, or self-sovereign DID document.
​

Why Can't Existing Card Authentication Handle Agents?

Existing 3-D Secure flows assume a human cardholder is present at checkout to complete a challenge. An AI agent cannot solve a CAPTCHA, receive an SMS OTP on the user's phone, or pass a biometric prompt. Networks classify agent traffic as card-not-present with no liability shift, which spikes decline rates and shifts chargeback exposure onto merchants. A purpose-built identity layer was required.
​

Mastercard's own April 2025 announcement framed the gap explicitly: "today's payment systems weren't built for AI agents to transact." Visa's Intelligent Commerce program described a parallel finding, that agent transactions were being blocked by issuer fraud rules trained on human session patterns. Both networks now layer agent-specific identity on top of EMV tokenization rather than replacing it.
​

How Does Mastercard Agent Pay Encode Agent Identity?

Mastercard Agent Pay issues an Agentic Token through the Mastercard Digital Enablement Service that binds three identities into one credential: the cardholder, the registered AI agent, and the scope of the mandate. When the agent presents the token at checkout, the network verifies the agent's certificate, decrypts the cardholder PAN, and enforces the mandate's spending limits before authorization.
​

Agents must be enrolled by their developer through Mastercard's program (announced with Microsoft, IBM, Braintree, and Checkout.com as launch partners). Enrollment produces a cryptographic agent ID that the network associates with the developer's KYC'd entity. At checkout, the token carries the agent ID alongside the cardholder token, letting the issuer score risk per agent rather than per session. See our full Mastercard Agent Pay explainer for the token lifecycle.
​

How Does Visa Trusted Agent Protocol Attest Agents?

Visa's Trusted Agent Protocol takes a different architectural choice. Rather than embedding agent identity in the payment token, it adds signed HTTP headers to the merchant request that attest the agent's identity, the user's consent, and the transaction intent. Merchants verify the signature against Visa's registry before routing the authorization, preserving the existing card rails.
​

The attestation header carries the agent operator's identifier, a user-consent reference, and a payload hash binding the attestation to the specific cart. Visa published the protocol in late 2025 as an open standard with Adyen, Cloudflare, and Stripe in the early signatory cohort. Because the protocol lives at the HTTP layer, it works with any underlying card brand. Compare the architecture side-by-side in our Agent Pay vs Trusted Agent breakdown.
​

How Do AP2's Verifiable Credentials Bind User Intent?

Google's Agent Payments Protocol (AP2) uses W3C Verifiable Credentials to make user consent cryptographically auditable. The protocol defines two mandate types: an Intent Mandate, which the user signs to authorize an agent to shop within a scope (e.g., "buy size-9 running shoes under $200"), and a Cart Mandate, signed when the agent presents the final cart for explicit human approval.
​

Each mandate is a VC issued by a wallet the user controls, signed with the user's key, and presented by the agent to the merchant or payment processor. The merchant verifies the signature and checks the mandate scope before charging. Google open-sourced the AP2 specification with more than 60 launch partners including Mastercard, American Express, PayPal, Coinbase, and Salesforce. For protocol depth see our AP2 protocol explainer.
​

How Do DIDs Verify Crypto-Native Agents?

Decentralized Identifiers (DIDs), standardized by the W3C in 2022, give an agent a self-sovereign identifier resolvable to a DID document containing public keys and service endpoints. A crypto-native agent settling in stablecoins on Base or Solana can sign a transaction with the key referenced in its DID document, and a counterparty can verify the agent by resolving the DID without consulting a central registry.
​

DIDs pair naturally with VC mandates: the user's wallet issues a VC delegating spending authority to the agent's DID, and the agent attaches the VC to onchain payments. AP2 explicitly supports DID-anchored issuers and holders, which is why protocols like Coinbase's x402 micropayment standard and Skyfire's agent-payment network use DIDs as the primary identity primitive for autonomous-agent commerce.
​

Identity Models Compared

The four models differ in trust anchor, transport, and how user consent is captured. The table summarizes the production characteristics relevant for merchants and developers choosing an integration path in 2026.

Model
​

Trust anchor
​

Transport
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User consent
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Best fit
​

Agentic Tokens (Mastercard Agent Pay)
​

Card network registry
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EMV token in authorization
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Tokenization enrollment + mandate scope
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Card-rails merchants on Mastercard
​

Trusted Agent Attestation (Visa)
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Visa agent registry
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Signed HTTP headers
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Consent reference in attestation
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Any card brand, HTTP-layer checkout
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Verifiable Credentials (AP2)
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User wallet (issuer-signed VC)
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VC presentation in protocol message
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Signed Intent + Cart Mandates
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Multi-rail (cards, ACH, stablecoins)
​

DIDs (W3C)
​

Self-sovereign DID document
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Onchain signature or DIDComm
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VC mandate to agent's DID
​

Crypto-native, stablecoin settlement
​

What Does the Consent Flow Look Like?

Across all four models the consent flow follows the same three-leg pattern. A human principal authorizes an agent with a scoped mandate. The agent shops within scope and presents a cart. The merchant verifies the agent's identity and the mandate's binding to the cart before settling. The verification step is what each protocol implements differently.
​

In a typical AP2 + Agent Pay hybrid flow, a user opens a wallet app, signs an Intent Mandate ("$500 monthly grocery budget, only at approved retailers"), and delegates to a registered agent. The agent fills a cart at an enrolled merchant. Before authorization, the merchant requests a Cart Mandate, which the user signs after reviewing the line items. The agent submits the Agentic Token plus the Cart Mandate VC. The issuer validates both before approving.
​

What Attacks Does Agent Identity Defend Against?

The threat model agent identity verification addresses includes rogue agents (unauthorized agents impersonating a registered one), replay attacks (reusing a captured mandate or token for a second transaction), scope escalation (an agent transacting outside its mandate), and merchant collusion (a merchant fabricating a mandate the user never signed). Each protocol layers defenses against this set.
​

Agentic Tokens defeat replay by binding each token to a single authorization window and a specific agent certificate. Trusted Agent headers prevent merchant collusion through user-consent references that are independently verifiable. AP2 Cart Mandates defeat scope escalation because the merchant must obtain a freshly signed mandate for each transaction. DIDs defeat impersonation by anchoring the agent's public key in a tamper-evident document the user can revoke. The remaining residual risk is principally key compromise, which falls back on wallet-level protections such as hardware-bound keys, biometric re-prompts, and revocation lists.
​

How Does Eco Fit Into Agent Identity?

Eco's orchestration layer settles agent payments in stablecoins across 15 chains, which means agents using AP2 or DID-based identity can route a verified mandate to the cheapest execution venue without human intervention. The Eco Routes API accepts a DID-signed payload, validates the attached mandate, and dispatches the transaction through Hyperlane or CCTP rails depending on destination chain.
​

For builders integrating agent commerce, the practical pattern is: use AP2 mandates for human-to-agent consent, use DIDs for agent-to-agent identity, and use Eco for the stablecoin settlement leg. See the Agent Pay implementation guide for the integration checklist.
​

Methodology and Sources

This article synthesizes primary documentation from the four protocol families plus the W3C identity standards underpinning them. All claims about partner cohorts, mandate types, and protocol mechanics trace to the original announcements and specifications listed below. Dated stats use Q1 2026 qualifiers where supply or partner counts change weekly.

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