Storage. The server keeps its data in SQLite (a file in the data
directory, the default) or PostgreSQL (database, KEEPORG_DATABASE_URL or
-database). Every row, the KDBX versions included, is sealed with
AES-256-GCM under a key derived from the master key and named by an HMAC.
The master key is required to start and a different one is refused. A data
directory from 0.10 or earlier is imported on first start. Several servers
may share one PostgreSQL database. Go goes to 1.26 for the pure-Go
drivers (modernc.org/sqlite, jackc/pgx).
Hardening, after an audit of the server, both clients and the deployment:
- Single sign-on approves a device only after an explicit Approve in the
browser that started it, bound by a cookie and PKCE; identities are never
linked by username, by verified email only when allowed, never to admins.
- Sign-in attempts are limited per address and per account, passwords are
checked outside the store lock with uniform timing, one-time codes work
once, and starting two-factor needs the password.
- Merge vaults bound KDF parameters, payload size and XML shape, check
pushes before storing them, and run at most two merges at once. A version
is written in the same transaction as its metadata.
- Tokens in URLs only on the event stream, which ends on revocation; CSP,
frame-ancestors, no-store and HSTS; sign-in CSRF; 404 for databases
without access; new trusted_proxies.
- Clients open only the server's approval page, keep case-variant and
retired file names apart, never overwrite a save made during a pull,
require https except locally, send the stream token in a header, bound
their reads and escape notifications and terminal output.
- The .deb creates the master key, systemd is sandboxed further, nginx sets
modern TLS and HSTS, and CI deploys from main only.
Server 0.12.0, desktop 0.6.0, Android 0.4.0 (versionCode 4).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Why: picking a winner is what a sync server does when it cannot read the
file. Once it can, the right answer is the union of both edits.
What: kdbx.Merge folds one database into another. Objects are matched by
UUID; the most recently modified version of each wins and the loser is filed
in the entry's history, so nothing is dropped. Deletions apply only when the
deletion is newer than the other side's edit, otherwise the edit resurrects
the object and the stale record is discarded. Groups keep their nesting,
objects move when the other side moved them later, database settings follow
Meta/SettingsChanged, and custom data and icons are unioned by key.
Attachments are remapped from the incoming pool into the target's, since an
entry that kept its old index would silently gain the wrong file.
Proved: twelve tests over independent additions, both conflict directions
with history, deletion, resurrection, nested groups, relocation, attachment
remapping, idempotence, order independence and settings. The last one
marshals a merged database and has keepassxc-cli decrypt an entry that only
ever existed in the incoming copy.
Why: merging two edits of a vault means decrypting it, so the server needs a
real KeePass implementation. Nothing else in this repository can be built on
guesswork about the format.
What: internal/kdbx reads and writes KDBX 4.0/4.1 with AES-256-CBC or
ChaCha20 payloads, AES-KDF or Argon2d/Argon2id derivation, and the ChaCha20
inner stream for protected values. ChaCha20, BLAKE2b and Argon2 are
implemented here, since the standard library has none of them and this
repository carries no third-party dependencies.
The XML payload is kept as a generic node tree rather than Go structs on
purpose: a merge server that dropped elements it did not model would silently
destroy data written by a newer KeePass. Anything unrecognised round-trips
untouched. Unsupported ciphers, KDFs and KDBX 3 files are reported as such
rather than guessed at, so a caller can fall back instead of losing data.
Proved: ChaCha20 against RFC 8439, BLAKE2b against RFC 7693, all three
Argon2 variants against RFC 9106. Round trips preserve unknown elements and
multi-line values; a wrong password, a flipped payload byte and a flipped
header byte are each rejected. Entry passwords appear nowhere in the file,
encrypted or merely compressed. And the part that actually matters:
keepassxc-cli 2.7.10 lists, reads and decrypts the protected values of a
vault this code wrote, including at the production Argon2d cost, and this
code reads back the file KeePassXC saves after editing it.
root