Files
keeporg/internal
root 5d66871527 Add a KDBX 4 codec: read, write, create
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.
2026-10-29 17:10:37 +01:00
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