# Visa Trusted Agent Protocol

HTTP message signatures prove the agent before checkout.

Cohorts: Mm

**Designed.** Protocol support is designed. The flow follows the protocol's published specification, with insimbi on the merchant side. Every check and every settlement is written to the record.

**Visa Trusted Agent Protocol.** Designed. HTTP message signatures (RFC 9421) prove the agent before checkout.

Lanes: Agent, Merchant edge, Agent key directory, insimbi

1. Agent: Sign the request: Signature-Input and Signature over the authority and path, with created time, nonce and keyid
2. Agent to Merchant edge: Request the page or checkout with the signature headers
3. Merchant edge to Agent key directory: Fetch the public key for the keyid
4. Agent key directory to Merchant edge: Public key
5. Merchant edge: Verify the signature, the domain and path, the time window and the nonce
6. Merchant edge to insimbi: Pay, with the verified agent attached
7. insimbi: Record the agent verification with the payment
8. insimbi to Merchant edge: Result

- [All flows](/docs/flows/): Every sequence diagram, linked to its section.
- [Integrations](/integrations/#protocols): Every agent protocol and rail we connect.
- [MCP tools](/docs/mcp/): insimbi as tools for any MCP client.

Request access: sales@insimbi.net

_insimbi is in early access with design partners._