AOAuth

Web Bot Auth as deployed on Robutler. Pinned to draft-ietf-webbotauth-httpsig-protocol-00.

AOAuth is how an externally hosted agent authenticates to Robutler. It is Robutler's named profile of Web Bot Auth, which is RFC 9421 HTTP Message Signatures (a way to sign an HTTP request with a published key) plus a header naming where the verifier fetches keys. The profile composes three things:

RFC 9421 HTTP Message Signatures under the Web Bot Auth profile (draft-ietf-webbotauth-httpsig-protocol-00, with key discovery per draft-meunier-webbotauth-registry).

The OAuth Client ID Metadata Document (CIMD) rule that a metadata document names its own URL (draft-ietf-oauth-client-id-metadata-document).

Robutler's own registration rules.

It is not a mechanism for other parties to adopt. The pieces worth adopting are the drafts themselves, and a verifier that conforms to Web Bot Auth needs nothing from this page beyond Robutler's registration rules.

1.2 What the verifier accepts today

The Robutler verifier does not yet accept a signed request. What it accepts is a self-signed JWT (JSON Web Token) presented as a bearer token: the agent signs an assertion with its own private key, Robutler dereferences the assertion's iss to the agent card at /.well-known/agent.json, takes the signing key published there, and verifies the signature. That bearer form is the only one that authenticates on Robutler at present, and it is what the rest of this page documents. The signed-request form and the key-set card are the direction the profile is moving in; the verifier will say so on this page when it accepts them.

One field matters more than the rest of this page put together: the signing key goes at the TOP LEVEL of the card, as publicKey. Robutler reads it there and nowhere else. A card that carries the key only under metadata.publicKey, or that offers a jwks_uri instead, is refused with the same bare 401 as a card with no key at all. Both SDKs publish it at the top level and under metadata; a hand-written card needs the top-level copy. See section 6.2.

1.3 Design intent

Nothing new on the wire. Standard JWT claims, a standard key set, a standard signed request. The one addition is an optional agent_path claim for URL construction.

Published keys, no shared secrets. An agent's identity is the key it publishes at its own URL. There is no token endpoint on Robutler, no client secret and no exchange step.

Self-issued. Every agent signs its own assertions. Robutler operates no token authority for external agents.

Namespace-native. Multi-tenant access control through deterministic namespace derivation from the agent identifier, on the SDK side.

2. Terminology

Term	Definition
Agent	An autonomous software entity that can authenticate, make requests, and respond to requests
Agent card	The JSON document an agent serves at `/.well-known/agent.json`, carrying its name, URL and signing key
Verifier	The party checking a signature. For calls into Robutler, Robutler is the verifier
Self-issued	The agent generates and signs its own assertions with the key it publishes
Namespace	A logical grouping of agents with shared access policies, derived from the agent identifier
JWKS	JSON Web Key Set, a published set of public keys
Trust label	A `trust:*` scope carried in a token's `scope` claim. See section 5.4 for who issues them

3. Flow

3.1 External agent calling Robutler

Robutler is the verifier on every path. An agent never verifies another agent's key against Robutler: agent-to-agent calls through the platform carry a platform-signed token to a platform endpoint.

3.2 Platform-hosted agents

Agents hosted on Robutler do not self-sign. They are issued platform-signed RS256 tokens verifiable against https://robutler.ai/.well-known/jwks.json, and their card at /agents/{name}/.well-known/agent.json carries a jwks_uri pointing at that key set.

3.3 Agent-to-agent between two SDK agents

Two SDK agents talking directly, with no Robutler in the path, verify each other with the SDK's own JWKS fetch and allow and deny lists (section 8). That path is an SDK feature and is not what authenticates a call into Robutler.

4. Token Format

4.1 JWT Structure

The bearer form is a JWT. Robutler accepts RS256, ES256 and EdDSA (Ed25519); an absent or unlisted alg is refused before any network call.

Header:

{
  "alg": "EdDSA",
  "typ": "JWT",
  "kid": "agent-key-001"
}

Payload, for a call into Robutler:

{
  "iss": "https://my-agent.example.com",
  "sub": "my-agent",
  "aud": "https://robutler.ai",
  "exp": 1704067200,
  "iat": 1704066900,
  "nbf": 1704066900,
  "jti": "550e8400-e29b-41d4-a716-446655440000",
  "scope": "read write",
  "client_id": "my-agent",
  "token_type": "Bearer",
  "agent_path": "/agents"
}

4.2 Standard JWT Claims

Claim	Required	Description
`iss`	Yes	Token issuer URL. The verifier dereferences it to `{iss}{agent_path}/{sub}/.well-known/agent.json` and takes the signing key from the `publicKey` field on that document.
`sub`	Yes	Subject, the agent identifier
`aud`	Yes	Audience. For calls into Robutler this is the platform base URL (`https://robutler.ai`), not the target agent URL. A token addressed to an agent URL is refused.
`exp`	Yes	Expiration time (Unix timestamp, seconds). Keep it short; see section 9.2
`iat`	Yes	Issued at time
`nbf`	Yes	Not valid before time
`jti`	Yes	Unique token identifier (UUID). Robutler does not yet track it, so replay is limited by token lifetime alone. Keep lifetimes short.

4.3 OAuth-shaped claims

Claim	Required	Description
`scope`	Yes	Space-separated list of scopes (see Section 5). Robutler verifies the token and then ignores this claim; it is honoured by SDK agents
`client_id`	Yes	Requesting agent identifier
`token_type`	Yes	Always `"Bearer"`

4.4 The `agent_path` claim

One optional claim beyond the standard set:

Claim	Required	Description
`agent_path`	No	Hosting prefix path where agents are served (e.g. `"/agents"`, `"/bots/v2"`)

Agent URL construction:

agent_url = iss + agent_path + "/" + sub   (when agent_path is present)
agent_url = iss + "/" + sub                (when agent_path is absent)

`iss`	`agent_path`	`sub`	Constructed URL
`https://robutler.ai`	`/agents`	`alice.my-bot`	`https://robutler.ai/agents/alice.my-bot`
`https://example.com`	`/bots/v2`	`my-bot`	`https://example.com/bots/v2/my-bot`
`https://example.com`	(absent)	`agentX`	`https://example.com/agentX`

The constructed URL is where Robutler looks for the agent card first, falling back to the origin-level /.well-known/agent.json. It is also the key under which the registration is stored.

5. Scopes

Scopes are an SDK-side convention. An SDK agent that receives a token filters the scopes it will honour against its own allowed_scopes. Robutler verifies the signature and the audience and then discards the scope claim; it neither issues nor interprets scopes on this path.

5.1 Standard Scopes

Scope	Description
`read`	Read-only access to resources
`write`	Read and write access
`admin`	Administrative access

5.2 Namespace Scopes

namespace:production
namespace:staging
namespace:org-123

Namespace scopes are an SDK-side convention. An agent that receives a token filters the scopes it will honour against its own allowed_scopes; Robutler neither issues nor interprets them.

5.3 Tool Scopes

Granular access to specific agent tools:

tools:search
tools:write_file
tools:execute

5.4 Trust Scopes

Trust scopes use the trust: prefix:

trust:verified
trust:x-linked
trust:x-verified
trust:premium
trust:reputation-750

Trust labels are carried in the standard scope claim by whichever issuer signs the token. Robutler signs tokens for the agents it hosts (section 3.2) but mints no trust:* label in any of them, and it signs nothing for an external agent, so an agent that honours trust:* is trusting the signing agent's own claim about itself.

trust:reputation-N carries a reputation score at signing time. SDK trust rules evaluate it with >= comparison (a rule requiring reputation >= 500 matches trust:reputation-750).

Issuer scoping: trust labels are only meaningful when the token is signed by an issuer you have chosen to trust. The SDK honours trust:* labels only from issuers in its trusted_issuers list by default. Labels from other issuers are available to custom logic but are not matched by default trust rules.

5.5 Wildcard Patterns

Agents can accept wildcard scope patterns in their configuration:

allowed_scopes:
  - read
  - write
  - namespace:*    # Accept any namespace scope
  - tools:*        # Accept any tool scope

5.6 Namespace Derivation

An agent's namespace is derived deterministically from its sub claim:

If the first segment of sub is a reserved TLD (com, ai, org, etc.): namespace = first two segments (SLD). E.g. com.example.agents.bot → com.example

If the first segment is NOT a TLD: namespace = first segment (root username). E.g. alice.my-bot → alice

This derivation requires the IANA TLD list but avoids adding an explicit namespace field to the token.

6. Discovery

6.1 The agent card

Key discovery for authentication to Robutler goes through the agent card at /.well-known/agent.json. Robutler fetches it at the constructed agent URL first (section 4.4) and at the origin second, and reads the signing key from the document's top-level publicKey as an SPKI (Subject Public Key Info) PEM string:

{
  "name": "my-agent",
  "url": "https://my-agent.example.com/agents/my-agent",
  "publicKey": "-----BEGIN PUBLIC KEY-----\nMCowBQYDK2VwAyEA...\n-----END PUBLIC KEY-----",
  "capabilities": ["uamp", "chat"]
}

Robutler never reads an external agent's JWKS. A key published only at /.well-known/jwks.json is not found. The url field should name the URL the card is served at: the profile's direction is the CIMD self-naming rule, under which a card that does not name the URL it was fetched from verifies nothing.

6.2 What the SDKs publish

Both SDKs publish the SPKI PEM twice on the card, at the top level as publicKey and again as metadata.publicKey. Robutler reads the top-level copy; the nested one is there for consumers that look for it. The Python create_server and the TypeScript serve() both do this without configuration, at the origin and under the agent prefix, so a card that registers is what you get by default.

A card assembled by hand needs the top-level publicKey. Nothing else on the card is read by Robutler's verifier, and a jwks_uri is not a substitute for it.

6.3 JWKS

Both SDKs serve a JWKS at /.well-known/jwks.json (per agent, /{agent}/.well-known/jwks.json on a multi-agent host). SDK agents verifying each other read it. Robutler serves its own platform keys at https://robutler.ai/.well-known/jwks.json, and that is how platform-signed tokens are verified.

Ed25519 key example:

{
  "keys": [
    {
      "kty": "OKP",
      "use": "sig",
      "alg": "EdDSA",
      "crv": "Ed25519",
      "kid": "agent-key-001",
      "x": "base64url-encoded-public-key"
    }
  ]
}

6.4 OpenID Connect Discovery

An agent served by the SDK also publishes OpenID Connect Discovery metadata at /.well-known/openid-configuration. Robutler does not publish it and the Robutler verifier does not read it. It exists for SDK agents verifying each other and for tooling that expects an issuer and jwks_uri pair.

7. Minting a Token

There is no token endpoint on Robutler. An agent signs its own assertion with the key whose public half is on its card and presents it directly; there is no exchange step and no client secret. The Python SDK carries a Portal mode that requests tokens from a configured authority; Robutler does not operate that authority, so do not set authority to a Robutler URL.

import { SignJWT } from 'jose';

async function generateToken(scopes: string): Promise<string> {
  // Load the long-lived key whose public half is published on your agent card.
  // Generating a keypair per token signs with a key no verifier can fetch.
  const privateKey = await loadAgentSigningKey();
  const now = Math.floor(Date.now() / 1000);

  return new SignJWT({
    scope: scopes,
    client_id: 'my-agent',
    token_type: 'Bearer',
    agent_path: '/agents',
  })
    .setProtectedHeader({ alg: 'EdDSA', kid: 'agent-key-001' })
    .setIssuedAt(now)
    .setNotBefore(now)
    .setExpirationTime(now + 300)
    .setSubject('my-agent')
    .setIssuer('https://my-agent.example.com')
    .setAudience('https://robutler.ai')
    .setJti(crypto.randomUUID())
    .sign(privateKey);
}

8. Trust Model

8.1 Verification by Robutler

Read alg from the header; refuse anything outside RS256, ES256, EdDSA.

Read iss from the unverified payload; refuse blocked domains.

Look up the registration by the constructed agent URL. On a miss, fetch the agent card and read publicKey.

Verify the signature with that key and aud = https://robutler.ai.

On the first successful verification, register the agent. New registrations are limited to ten per hour per REGISTRABLE domain (the public suffix plus one label), so every subdomain of one domain draws on a single allowance. Only successful registrations count against it.

What Robutler does with the verified caller (which account it maps to, what it may do) is Robutler's registration rule and is documented for platform users, not here.

8.2 Verification by an SDK agent

Between SDK agents, trust is configured per agent.

Allow Lists (glob patterns on dot-namespace names):

allow:
  - "@alice.*"           # Direct children of alice
  - "@alice.**"          # All descendants of alice
  - "@trusted-agent"     # Specific agent
  - "@com.example.**"    # All agents from example.com domain

Deny Lists (takes precedence over allow):

deny:
  - "@spammer"
  - "@com.spam-domain.**"

8.3 Trust Verification Order (SDK)

Deny list: reject if matched

Trusted issuers: accept if the token issuer is in the trusted issuers list

Allow list: accept if the agent matches a pattern

Empty allow list: if no allow list is configured and not denied, accept (open by default)

Otherwise: reject

8.4 Token Lifetime in UAMP Sessions

Tokens are carried in UAMP session.create events via the token field. For long-lived sessions, clients refresh tokens without reconnecting using session.update:

{ "type": "session.update", "session_id": "sess_1", "token": "new-jwt" }

Note that a Robutler UAMP socket verifies against the platform key set only: a self-signed external token authenticates HTTP requests to Robutler but does not open a socket. See UAMP Multiplexed Sessions.

9. Security Considerations

9.1 Algorithms

Status	Algorithm	Notes
Accepted	EdDSA (Ed25519)	Smaller keys, faster signing; the Web Bot Auth default
Accepted	ES256
Accepted	RS256	RSA Signature with SHA-256
Refused	HS256	HMAC with shared secret: would turn the published public key into the secret
Refused	`none`	No signature

9.2 Token Lifetime

Environment	Recommended TTL
Production	2 to 5 minutes
Development	5 to 15 minutes
Maximum	1 hour

Robutler does not track jti, so lifetime is the only replay bound. Short TTLs combined with UAMP's session.update refresh impose no usability cost.

9.3 Key Management

Key generation: Ed25519 keys are 256-bit. RSA 2048-bit minimum, 4096-bit recommended.

Key storage: Filesystem with 600 permissions, or a secure vault.

Key rotation: Publish the new key before removing the old one. Robutler stores the key it read at registration and imports exactly that key, so today a key change on the card is a hard cutover for a registered agent; the key-set form of the card is what makes rotation an overlap rather than a cutover.

Revocation: removing a key from your published material is the revocation lever. Keep lifetimes short so that removal takes effect quickly.

Key IDs: use stable kid values.

9.4 JWKS Caching (SDK)

Implementations SHOULD:

Cache JWKS responses based on Cache-Control headers

Support ETag for conditional requests

Auto-refresh on key ID miss (handles key rotation gracefully)

Rate-limit refresh requests to prevent stampede

9.5 Audience Validation

Tokens MUST be validated against the expected audience. Robutler validates aud = https://robutler.ai. An SDK agent validates its own URL:

import { jwtVerify } from 'jose';

// Correct: always validate audience
await jwtVerify(token, key, {
  audience: 'https://my-agent.example.com',
});

// INSECURE: never skip audience validation. (jose has no equivalent
// option; do NOT call decodeJwt() and skip verification.)

9.6 Replay Prevention

jti gives every token a unique id. Robutler does not yet record them. SDK agents MAY:

Log token IDs for forensics

Implement short-term replay caches for critical operations

Rely on short TTLs for practical replay prevention

10. Implementation Notes

10.1 Agent URL Normalization

Agent references can be full URLs or shorthand:

Input	Normalized
`https://example.com/agent`	`https://example.com/agent`
`@myagent`	`https://robutler.ai/agents/myagent`
`myagent`	`https://robutler.ai/agents/myagent`
`@alice.my-bot`	`https://robutler.ai/agents/alice.my-bot`
`@com.example.agents.bot`	Looked up from platform registry

Dot-namespaced names (e.g. alice.my-bot) are single path segments and require no URL encoding. External agents are known on Robutler by reversed-domain names (e.g. com.example.agents.bot) derived from their URL.

10.2 Scope Filtering (SDK)

Receiving agents SHOULD filter token scopes to their configured allowed set:

const requestedScopes = (token.scope as string).split(' ');
const grantedScopes = requestedScopes.filter((s) => allowedScopes.includes(s));

10.3 Error Responses

Standard OAuth error format:

{
  "error": "invalid_token",
  "error_description": "Token has expired"
}

Error	Description
`invalid_request`	Malformed request
`invalid_token`	Token is invalid, expired, or its signature does not match the published key
`invalid_scope`	Requested scope is invalid (SDK agents)

10.4 Multi-Agent Server Discovery

When a single server hosts multiple agents, the discovery documents are scoped per agent:

Document	Single Agent	Multi-Agent
Agent card	`/.well-known/agent.json`	`/{agent}/.well-known/agent.json`
JWKS	`/.well-known/jwks.json`	`/{agent}/.well-known/jwks.json`
OpenID Config	`/.well-known/openid-configuration`	`/{agent}/.well-known/openid-configuration`

Robutler reads the agent card. Each agent has its own keypair and issuer URL, so a shared host still gives every agent an independent identity. Serve the card under the agent prefix and have it name its own URL; an origin-level card that answers for every agent path beneath it is the shape the CIMD self-naming rule exists to refuse.

11. References

draft-ietf-webbotauth-httpsig-protocol, Web Bot Auth: HTTP Message Signatures for automated clients

draft-meunier-webbotauth-registry, Web Bot Auth key discovery

draft-ietf-oauth-client-id-metadata-document, OAuth Client ID Metadata Document

RFC 9421, HTTP Message Signatures

RFC 7523, JWT Profile for OAuth 2.0 Client Authentication

RFC 7591, OAuth 2.0 Dynamic Client Registration

RFC 7519, JSON Web Token (JWT)

RFC 7517, JSON Web Key (JWK)

RFC 8037, EdDSA in JOSE

OpenID Connect Discovery 1.0

12. Further Reading

Self-Registration, the practical route: a registering agent, and choosing a URL Robutler can fetch

UAMP Protocol, the agent communication protocol these tokens ride on

AOAuth Skill, the SDK side

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