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keeporg/docs/PROTOCOL.md
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root a9308a3e89 Merge concurrent saves on the server, with vaults created from the web
Why: the point of a sync server is that two people can work at once. Picking
a winner was all this one could do while it could not read a vault.

What, end to end:
- A vault is created at /web or with `keeporg vault -create`: the server
  builds an empty KDBX 4 file, encrypts it with the password from the form,
  and stores it as version 1. An existing database can adopt a stored key
  with `keeporg db -id <id> -store-password`, which is verified against the
  stored file before it is accepted.
- A stale push to a `merge` vault is no longer refused. The server opens the
  stored version and the pushed one in memory, folds them together, and
  stores the re-encrypted result. Clients push as usual and pull what comes
  back. Any failure answers 409 merge_failed and the client keeps its copy
  aside, so a failed merge still loses nothing.
- At rest: vault contents stay KDBX-encrypted as always. A merge vault's
  password is kept AES-256-GCM-wrapped under a master key that lives outside
  the data directory, bound to the vault id, never returned by the API. A
  stolen data directory is ciphertext; a stolen data directory plus the
  master key is not. The server runs without a master key and simply refuses
  to create or merge vaults.

This moves the server inside the trust boundary for vaults it can merge,
which is inherent to merging and is stated plainly in the README, the
handover notes and the web form itself. Key-less strategies are unchanged and
remain the default for a database created without a password.

Proved: two clients editing the same version are merged rather than refused,
the newer edit of one entry wins, a merge failure leaves the stored vault
untouched, `merge` is refused without a stored key, the wrapped key never
appears in state.json or the API, and the web interface rejects a form
without its CSRF token, withholds its cookie over plain http, and only offers
groups the user administers. Checked by hand against the real thing: a vault
created in a browser, edited by keepassxc-cli on two sides from the same
version, merged by the server, and both entries read back out with
keepassxc-cli. make check, make test-race, android lint and both .deb builds
are clean.
2026-10-29 17:34:47 +01:00

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# KeepOrg HTTP API
Every `/api/` endpoint takes and returns JSON and needs
`Authorization: Bearer <token>`, except the login, device and invite
endpoints. Errors carry `{"code": "...", "error": "..."}`; `code` is stable
and meant to be matched on, `error` is for humans.
HTML is served at `/web` (sign in, list vaults, create one) and at `/device`,
`/invite/{token}` and `/oidc/callback`. The web pages use the same session
tokens in a cookie that is `HttpOnly`, `SameSite=Strict` and `Secure` behind
https, and every form carries a per-session CSRF token.
## Authentication
| Method | Path | Body | Answer |
| --- | --- | --- | --- |
| POST | `/api/v1/auth/login` | `{username, password, totp, label}` | `{token, expires_at, user}`; `401 totp_required` when a second factor is enrolled and missing, `401 totp_invalid`, `401 bad_credentials` |
| POST | `/api/v1/auth/logout` | – | revokes the calling token |
| GET | `/api/v1/auth/whoami` | – | the account and its group memberships |
| POST | `/api/v1/auth/totp/enroll` | – | `{secret, uri}`; not active until confirmed |
| POST | `/api/v1/auth/totp/confirm` | `{code}` | `{totp_enabled: true}` |
| POST | `/api/v1/auth/device/start` | `{label}` | `{device_code, user_code, verification_url, interval, expires_in}` |
| POST | `/api/v1/auth/device/poll` | `{device_code}` | `202 {status: "pending"}`, then `200 {token, ...}` once; `410 expired` |
A device code is single use: the first successful poll consumes it.
## Synchronization
| Method | Path | Notes |
| --- | --- | --- |
| GET | `/api/v1/databases` | `{databases: [{id, name, perm, merge_strategy, version, sha256, size, updated_at, updated_by}]}` |
| GET | `/api/v1/databases/{id}/blob` | bytes; `ETag: "<version>"`, `X-KeepOrg-SHA256`; `204` when the database has no content yet; `?version=<n>` reads a stored older version |
| PUT | `/api/v1/databases/{id}/blob` | body is the KDBX file. `If-Match` is required |
| GET | `/api/v1/events` | SSE. Accepts `?access_token=` because an event stream cannot always set headers |
### PUT semantics
`If-Match` carries the version the edit was based on, or `*` to force.
| Condition | Status | Body |
| --- | --- | --- |
| `If-Match` missing | `428 precondition_required` | – |
| version matches, bytes differ | `200` | `{version, sha256, unchanged: false}` |
| version matches, bytes identical | `200` | `{version, sha256, unchanged: true}` |
| version stale, strategy is `merge` | `200` | `{version, sha256, merged: true, merge_summary, based_on}` — the two copies were folded together and the result stored as a new version |
| version stale, strategy is `merge`, but merging failed | `409 merge_failed` | `{error, current_version, merge_strategy}`; the stored vault is untouched |
| version stale, any other strategy | `409 conflict` | `{current_version, merge_strategy}`, plus `ETag` and `X-KeepOrg-Strategy` |
| `If-Match: *`, strategy is `client-wins` | `200` | the server copy is replaced |
| `If-Match: *`, any other strategy | `409 force_not_allowed` | – |
| read-only access | `403 forbidden` | – |
| no access | `404 not_found` | a database you cannot read does not exist to you |
| larger than `max_db_size_mb` | `413 too_large` | – |
`X-KeepOrg-SHA256` on a `PUT` is optional; when present it must match the
body or the request is rejected with `400 checksum_mismatch`.
After any accepted push, compare the `sha256` in the answer with what you
sent. If they differ the server stored something else — a merge — and the
local copy must be replaced by a fresh `GET`.
### Events
```
event: db-updated
data: {"type":"db-updated","database_id":"...","name":"Team","version":7,"sha256":"...","by":"alice"}
event: db-list-changed
data: {"type":"db-list-changed","database_id":"..."}
```
`db-updated` follows an accepted push; `db-list-changed` follows a grant,
rename, strategy change or deletion. A comment line (`: keepalive`) arrives
every 25 seconds. Reconnect on any error and reconcile fully; events are
notifications, never state.
## Vaults
A vault is a database the server created and can open. Creating one is the
only way the server comes to hold a KDBX key, and the only strategy that
needs one is `merge`.
| Method | Path | Body | Needs |
| --- | --- | --- | --- |
| POST | `/api/v1/vaults` | `{name, owner_group_id, merge_strategy, password}` | group admin of the owner |
| POST | `/api/v1/databases/{id}/key` | `{password}` or `{forget: true}` | database admin |
`POST /api/v1/vaults` builds an empty KDBX 4 database, encrypts it with
`password`, stores it as version 1 and answers with the database view. The
password must be at least 12 characters. For `merge_strategy: "merge"`
(the default here) the password is kept, encrypted under the server's master
key; for every other strategy it is used once and forgotten. A server with no
master key refuses with `400`.
`POST /api/v1/databases/{id}/key` stores the password of a database that
already has content, after checking that it opens the stored version, which
is how an uploaded database becomes mergeable. `{"forget": true}` removes it;
that is refused while the strategy is still `merge`.
The wrapped key is never returned by any endpoint.
## Administration
Permission needed is in the last column. "Group admin" means administering
the group named or any group above it.
| Method | Path | Body / query | Needs |
| --- | --- | --- | --- |
| GET | `/api/v1/groups` | – | any account; lists what you can see |
| POST | `/api/v1/groups` | `{name, parent_id}` | group admin of the parent; server admin for a root group |
| DELETE | `/api/v1/groups/{id}` | – | group admin; refuses while it has children, members or databases |
| POST | `/api/v1/groups/{id}/members` | `{username or user_id, role}` | group admin |
| DELETE | `/api/v1/groups/{id}/members/{user}` | – | group admin |
| POST | `/api/v1/databases` | `{name, owner_group_id, merge_strategy}` | group admin of the owner |
| PATCH | `/api/v1/databases/{id}` | `{name?, merge_strategy?}` | database admin |
| DELETE | `/api/v1/databases/{id}` | – | database admin; deletes every stored version |
| POST | `/api/v1/grants` | `{group_id, database_id, perm}` | database admin |
| DELETE | `/api/v1/grants` | `?group_id=&database_id=` | database admin |
| POST | `/api/v1/invites` | `{group_id, role, ttl_hours, max_uses}` | group admin |
| GET | `/api/v1/invites` | – | your own invites, and those of groups you administer |
| GET | `/api/v1/users` | – | yourself, plus members of groups you administer |
| GET | `/healthz` | – | unauthenticated liveness |
`merge_strategy` is one of `merge`, `server-wins`, `client-wins`, `manual`.
Switching to `merge` requires a stored key and is otherwise refused with
`400`. `perm` is one of `read`, `write`, `admin`. `role` is `member` or
`admin`.