API-Key Session Credentials for the Agent Enrollment Protocol

Introduction AEP session credentials allow a Service to issue a stateful credential after an Agent authenticates with a baseline AEP client assertion . This document defines the api-key grant type for Services that want to reuse existing API-key middleware while preserving AEP key possession as the issuance root. Extension request and response bodies are JSON objects carried over HTTP semantics as defined by AEP. This extension does not replace baseline AEP authentication. Services that implement this extension MUST continue to accept baseline AEP authentication on authenticated AEP commands.

Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Grant Type The grant type identifier is:

A Service that supports this extension lists api-key in commands.grant_types and lists grant and revoke in commands.supported in its AEP Inspect document.

Inspect Configuration A Service MAY publish configuration under commands.grant_types_config.api-key:

default_lifetime_seconds is an AEP-owned numeric value and is therefore represented as a JSON string. header_names, when present, lists HTTP header names the Service can accept for API-key presentation. Header names are case-insensitive on the wire, but Services SHOULD publish lowercase names. If absent, the default header name is x-api-key. scopes_supported, when present, lists Service-defined scope strings an Agent can request. supports_per_credential_revoke is a string boolean. If absent, the default is "false". A Service that returns credential_id in a Grant response MUST support Revoke with that credential_id. A Service that does not support per-credential Revoke MUST omit credential_id from Grant responses.

Grant Request The Agent invokes AEP Grant using baseline Authorization: AEP <jwt> authentication with op equal to grant.

grant_type MUST be api-key. label is OPTIONAL and is an Agent-provided display label. Services MAY ignore it. requested_scopes is OPTIONAL. A Service MAY grant fewer scopes than requested. Unsupported requested scopes MAY be omitted from the response scopes array. If the Service cannot issue a useful credential for the requested scopes, it MUST return invalid_request.

Grant Response A successful Grant response is a JSON object:

api_key is REQUIRED and contains the opaque API key value. Services MUST generate API key values with at least 128 bits of entropy. Agents MUST treat the value as an opaque bearer secret. API key values MUST match the following syntax. Numeric character values and repetition operators are defined by RFC 5234 .

This syntax permits visible ASCII characters while excluding whitespace, control characters, double quote, comma, semicolon, and backslash. The restricted character set avoids header parsing ambiguity when API keys are presented in HTTP field values. header is REQUIRED and identifies the HTTP header used for presentation. When header_names is advertised, the value MUST be one of the advertised names. expires_at is REQUIRED and is an RFC 3339 timestamp for credential expiry. scopes is REQUIRED and contains the granted scope strings. The Service MAY return an empty array when the API key has no scope-limited authorization. credential_id, when present, is a stable identifier for per-key Revoke. If present, the Service MUST support Revoke with this value. Services MUST issue expiring API keys.

Credential Presentation On later HTTP requests, the Agent presents the API key in the response-selected header:

Authenticated AEP command endpoints MUST continue to accept baseline AEP authentication.

Revoke The Agent invokes AEP Revoke using baseline Authorization: AEP <jwt> authentication with op equal to revoke. To revoke all API keys of this type for the authenticated Agent:

To revoke one API key when the Service returned credential_id:

Revoke returns an empty JSON object on success. The Service MUST return success regardless of whether a matching key existed. To revoke all session credentials of every grant type, Agents use the core all_grant_types Revoke request.

Error Handling This extension uses the AEP error vocabulary defined by the core protocol. An API key that is expired, malformed, revoked, unknown, or bound to a different Agent fails as not_recognized.

IANA Considerations This document requests registration of api-key in the AEP Grant Types registry. Field Value Grant Type api-key Description Opaque API key issued through AEP Grant Reference This document

Security Considerations API keys are bearer secrets. Services MUST store only salted hashes or equivalent one-way verifiers. Services MUST NOT log raw API-key values, and Services MUST support AEP Revoke for every advertised grant type. Agents that suspect key disclosure SHOULD call AEP Revoke using baseline AEP authentication and then fall back to per-request signed client assertions until a new key is issued. Services MUST validate only the configured API-key header for this extension. Services SHOULD reject ambiguous requests that present multiple API-key headers or multiple non-baseline bearer credentials when that ambiguity would affect authorization semantics.

Privacy Considerations API keys can become correlation handles if reused outside the issuing Service. Agents MUST NOT present AEP-issued API keys to other Services. Services MUST NOT log raw API-key values in ordinary logs or telemetry.