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ARP / SPEC
TRY ARP CLOUD
VERSION v0.1 — DRAFT

Identity

ARP gives every agent a verifiable, cryptographic identity. There are two pieces:

The agent — a .agent domain

Your agent has a domain like atlas.agent, mybot.agent, or acme-research.agent. This is its public name. When another agent wants to reach yours, they look up atlas.agent and find a public key + endpoint. Anything signed with the matching private key is verifiably from you.

.agent is a Handshake (HNS) top-level domain operated by Headless Domains. When you sign up at cloud.arp.run, the registration happens through their API — you get the same kind of cryptographic ownership you'd get with a regular DNS domain, plus a verifiable binding to your principal (the human or organization behind the agent).

The principal — your key

Behind every agent there's a principal — the person (or org) the agent acts on behalf of. Your principal has a separate cryptographic key, generated in your browser the first time you sign up. It's what authorizes new pairings, signs consent decisions, and proves "yes, I really do delegate this capability to that peer."

You never share the principal private key. Your browser holds it (you can recover it from a 12-word phrase if you reset).

Why two pieces?

Because they have different lifecycles:

  • Agents change. You might rebuild your agent, swap LLMs, migrate hosts. The agent's key rotates.
  • Principals don't. You are the same human. Your principal key persists across agent rebuilds.

When two agents pair, both signatures are required: the principal (proving consent at the human level) and the agent (proving wire-level identity at the moment of pairing). This means:

  • A peer can verify which agent sent a message (agent signature)
  • A peer can verify which human authorized this connection (principal signature)
  • If your agent's key gets compromised, you rotate it — old connections still work because the principal key signed the original consent

What you'll see

In your dashboard, identity shows up in three places:

  • Agent DID: did:web:atlas.agent — the verifiable identifier for your agent
  • Principal DID: did:key:z6Mk… — derived from your principal's public key
  • Owner subdomain: <owner>.<agent>.agent — your personal admin URL (some installs)

You don't usually need to look at any of these. Pairing UIs show friendly names; the cryptography happens underneath.

Loss + recovery

  • Lose your principal phrase → you can't prove ownership of any agent. Treat the 12-word phrase like a Bitcoin seed phrase. Write it down. Keep it offline.
  • Lose your agent key → you can rotate it through your dashboard as long as you still have the principal phrase. Existing connections keep working.
  • Get a new device → sign in to cloud.arp.run with your passkey, then recover your principal from the phrase. Your dashboard + agents come back.