GET /api/principals/{id}

Read one principal by id.

Authentication

Send the session id as Authorization: Bearer <session id>, and an RFC 9449 DPoP proof in the DPoP header if your session is bound to a key. The two are required together, not as alternatives — see Authenticating and Proving you hold your key.

This surface sets no cookie

There is no session cookie on any response and none is read on any request. Do not set credentials: "include" on a browser fetch.

Parameters

Name	In	Required	Type	Description
id	path	yes	string	A principal id as 16 hex digits. This is the id field of a principal projection -- NOT the principalId decimal string beside it. The two are the same eight bytes in two spellings, and only the hex one is a path segment.

Request

No request body.

Responses

200

The principal.

Field	Type	Required	Description
principal	Principal	yes	A principal, carrying its id in BOTH spellings because different routes take different ones. id (16 hex digits) is what this API's {id}, {gid} and {pid} path segments take; principalId (a decimal string of the same eight bytes) together with systemId is what the ACL and export routes take.

Principal

Field	Type	Required	Description
id	string	no	16 hex digits.
principalId	string or null	no	The same eight bytes as a decimal string. A string, so that an id above 2^53 survives.
systemId	integer or null	no	Assigned by the key server at setup. READ IT FROM THE SERVER; a hardcoded value addresses a principal that does not exist and yields a misleading "unknown principal".
className	string or null	no	The key server's own class name -- UserAndPasswordInfo, TransportPrincipalInfo, LdapPrincipalInfo, XAuthPrincipalInfo or GroupInfo.
name	string or null	no
disabled	boolean or null	no
roleIds	array of string	no
groupIds	array of string	no

Example

{
  "principal": {
    "id": "...",
    "principalId": "...",
    "systemId": 0,
    "className": "...",
    "name": "...",
    "disabled": true,
    "roleIds": [
      "..."
    ],
    "groupIds": [
      "..."
    ]
  }
}

400

BAD_REQUEST -- the id is not 16 hex digits. Note it is the id field, not principalId.

401

No live session, or a DPoP proof that did not verify.

SESSION_NOT_FOUND -- the credential names no session this Gateway holds. SESSION_EXPIRED -- it aged out. Both carry reauth: true; obtain a new credential rather than retrying.

PROOF_* -- the sender constraint refused. See the DPoP section of this document for the full table; PROOF_MALFORMED is a 400 and PROOF_REPLAY_CACHE_FULL a 503, and the rest are here.

SCOPED_CREDENTIAL_EXPIRED -- a scoped browser credential passed its fixed lifetime. Use does not extend it: an idle timeout would be refreshed by exactly the traffic a stolen handle produces.

403

Authenticated, and refused. The codes differ in what they say about where the refusal came from: ACCESS_DENIED and PRINCIPAL_DISABLED are the key server's, while NOT_WRITABLE, BUILT_IN_PRINCIPAL, OWN_ACCOUNT and OBJECT_NOT_IN_CREDENTIAL_SCOPE are decided by the Gateway before anything is sent.

404

NOT_FOUND.

500

A fault rather than a refusal.

OP_FAILED is the catch-all: the key server refused in words that match no classified pattern, so the Gateway cannot say more than that the operation did not happen. Some key server refusals that are conceptually a caller error arrive here rather than as a 4xx, because the wire carries no distinguishing code -- where a route can recognise one from its message it maps it, and each such mapping is documented on the operation.

503

A capacity ceiling or a missing deployment prerequisite. retryable says which.

A scope of session or process names the ceiling that was hit, and the response carries Retry-After.

Error handling

Every failure answers JSON carrying at least code and detail. Match on code — detail is written for a human debugging the call and its wording is not part of the contract. See the error model.

Status	Meaning
400	BAD_REQUEST -- the id is not 16 hex digits. Note it is the id field, not principalId.
401	No live session, or a DPoP proof that did not verify. SESSION_NOT_FOUND -- the credential names no session this Gateway holds. SESSION_EXPIRED -- it aged out. Both carry reauth: true; obtain a new credential rather than retrying. PROOF_* -- the sender constraint refused. See the DPoP section of this document for the full table; PROOF_MALFORMED is a 400 and PROOF_REPLAY_CACHE_FULL a 503, and the rest are here. SCOPED_CREDENTIAL_EXPIRED -- a scoped browser credential passed its fixed lifetime. Use does not extend it: an idle timeout would be refreshed by exactly the traffic a stolen handle produces.
403	Authenticated, and refused. The codes differ in what they say about where the refusal came from: ACCESS_DENIED and PRINCIPAL_DISABLED are the key server's, while NOT_WRITABLE, BUILT_IN_PRINCIPAL, OWN_ACCOUNT and OBJECT_NOT_IN_CREDENTIAL_SCOPE are decided by the Gateway before anything is sent.
404	NOT_FOUND.
500	A fault rather than a refusal. OP_FAILED is the catch-all: the key server refused in words that match no classified pattern, so the Gateway cannot say more than that the operation did not happen. Some key server refusals that are conceptually a caller error arrive here rather than as a 4xx, because the wire carries no distinguishing code -- where a route can recognise one from its message it maps it, and each such mapping is documented on the operation.
503	A capacity ceiling or a missing deployment prerequisite. retryable says which. A scope of session or process names the ceiling that was hit, and the response carries Retry-After.