omemo_dart/README.md

# omemo_dart

[![status-badge](https://ci.polynom.me/api/badges/16/status.svg)](https://ci.polynom.me/repos/16)

`omemo_dart` is a Dart library to help developers of Dart/Flutter XMPP clients to implement
[OMEMO](https://xmpp.org/extensions/xep-0384.html) in its newest version - currently 0.8.3.

The library provides an implementation of the [X3DH](https://signal.org/docs/specifications/x3dh/)
key exchange, the [Double Ratchet](https://signal.org/docs/specifications/doubleratchet/) with
the OMEMO 0.8.3 specific `ENCRYPT`, `DECRYPT` and `KDF_*` functions and a very high-level
`OmemoSessionManager` that manages all Double Ratchet sessions and provides a clean and simple
interface for encrypting a message for all known Ratchet sessions we have with a user.

This library also has no dependency on any XMPP library. `omemo_dart` instead defines an
intermediary format for the required data that you, the user, will need to transform to and from
the stanza format of your preferred XMPP library yourself.

## Important Notes

- **Please note that this library has not been audited for its security! Use at your own risk!**
- This library is not tested with other implementations of OMEMO 0.8.3 as I do not know of any client implementing spec compliant OMEMO 0.8.3. It does, however, work with itself.

## Usage

Include `omemo_dart` in your `pubspec.yaml` like this:

```yaml
# [...]

dependencies:
  omemo_dart:
    hosted: https://git.polynom.me/api/packages/PapaTutuWawa/pub
    version: ^0.5.0
  # [...]

# [...]
```

### Example

This repository includes a documented ["example"](./example/omemo_dart_example.dart) that explains the basic usage of the library while
leaving out the XMPP specific bits. For a more functional and integrated example, see the `omemo_client.dart` example from
[moxxmpp](https://codeberg.org/moxxy/moxxmpp).

### Persistence

By default, `omemo_dart` uses in-memory implementations for everything. For a real-world application, this is unsuitable as OMEMO devices would be constantly added.
In order to allow persistence, your application needs to keep track of the following:

- The `OmemoDevice` assigned to the `OmemoManager`
- `JID -> [int]`: The device list for each JID
- `(JID, device) -> Ratchet`: The actual ratchet

If you also use the `BlindTrustBeforeVerificationTrustManager`, you additionally need to keep track of:

- `(JID, device) -> (int, bool)`: The trust level and the enablement state

## Contributing

When submitting a PR, please run the linter using `dart analyze` and make sure that all
tests still pass using `dart test`.

To ensure uniform commit message formatting, please also use `gitlint` to lint your commit
messages' formatting.

## License

Licensed under the MIT license.

See `LICENSE`.

## Support

If you like what I do and you want to support me, feel free to donate to me on Ko-Fi.

[<img src="https://codeberg.org/moxxy/moxxyv2/raw/branch/master/assets/repo/kofi.png" height="36" style="height: 36px; border: 0px;"></img>](https://ko-fi.com/papatutuwawa)