The trust transport for
autonomous AI agents.
ATTP is the synchronous wire-level transport that carries cryptographically-signed messages between AI agents. Every byte verified. Every connection origin-bound. No consent dialogs, no bearer tokens, no replay.
Cryptographic identity at the wire level, not the session level.
OAuth bearer tokens stop at the connection. Consent dialogs trust the human, not the agent. ATTP signs every message with the agent's ECDSA key and binds it to the server's origin. Tampering is detectable. Replay is impossible. Server impersonation breaks at the connection check.
Origin-bound agent passports
Every agent carries a signed passport that names the server origin it is authorised to communicate with. A redirected proxy cannot satisfy the origin check, so MITM dies at the handshake.
Per-message ECDSA signing
Every JSON-RPC frame is signed with the agent's private key. The receiver verifies the signature against a JWKS endpoint before processing. Non-repudiable, tamper-evident, per-call.
Replay protection by design
Every message carries a unique nonce and a bounded timestamp. The receiver maintains a short-lived nonce store. A captured request cannot be replayed even one second later.
Trust levels L0 to L4
Agents carry a verifiable trust level. Self-signed is capped at L0. Issuer-attested climbs to L4. Servers refuse calls below the policy threshold for the endpoint. Verifiable, policy-driven, zero ambiguity.
Tool integrity pinning
Tool definitions are signed by their author and hash-pinned by the agent. A server that swaps a tool description between schema and execution is detected immediately. No silent rug-pulls.
OAuth + DPoP composable, not replaced
ATTP does not replace your existing authorisation stack. It adds an identity layer above OAuth bearer tokens and beyond DPoP. Drop-in alongside what you already have.
What an ATTP envelope looks like.
Real envelope from the live demo at /agents. ECDSA P-256, RFC 8785 canonical JSON, RFC 8941 structured header. Open the demo, sign one yourself.
{
"attp": {
"keyid": "alice-pa.example.com#3f6a",
"alg": "ES256",
"ts": 1715630537,
"nonce": "a3F-9k_pq2C",
"trust": "L3",
"origin": "consultant-bob.example.com",
"body_sha256": "5b8c...e29f",
"sig": "MEUCIQDp...Bw=="
},
"body": {
"type": "booking_confirm",
"selected_slot": "2026-05-19T10:00Z",
"agreed_price_gbp": 150,
"request_invoice": true
}
}
Where ATTP already lives in the public record.
Five independent dated artefacts at IETF, OpenAPI, OWASP, UKIPO and on-disk reference implementations. Verifiable by anyone, dated before any "first" press claim.
Production deployments using the protocol today.
Real systems carrying real value over ATTP-signed transport, in financial services and developer infrastructure.
LATTP -- Lightning binding
Agent-to-agent Bitcoin Lightning payments under ATTP-signed transport. GCP Cloud KMS HSM seed, FIPS 140-2 cryptographic module. Live at api.lattp.co.uk.
AgentPass
Agent identity and trust scoring (L0 to L4) with live sanctions screening against UK HMT and OFAC SDN. The identity authority behind ATTP passports.
MCPSaaS
Managed secure MCP proxy. Drops ATTP transport between agents and MCP servers with no code change to either side.
Live demo — SQL gate
Real database protected by L0-L4 trust gating. Try to drop a table with the wrong trust level. Watch ATTP refuse the operation before the SQL even runs.
Live demo — AI assistants book a paid call
Two AI personal assistants negotiate a 30-min paid consultation under live ATTP signing. Calendar slot picked, invoice issued, Lightning payment confirmed. Tamper with the invoice, watch verification fail. Strip the protocol, watch the silent overpayment.
Legacy ATTP page
Earlier release of the ATTP overview and trust-level walkthrough. Preserved for reference and external linking.
Want to integrate ATTP into your stack?
Reference SDKs on npm, PyPI, and Go modules. IETF draft is public reading. Production reference at api.lattp.co.uk. We are open to compare-notes calls with anyone working seriously on cryptographic identity for autonomous AI agents.
Get in touch →