1. Lookout for interesting issues on Github. We have tagged issues were we explicitly like to see contributions: https://github.com/open-keychain/open-keychain/labels/help-wanted
2. Read this README, especially the notes about coding style
3. Fork OpenKeychain and contribute code (the best part :sunglasses: )
4. Open a pull request on Github. We will help with occuring problems and merge your changes back into the main project.
We are using the newest [Android Studio](http://developer.android.com/sdk/installing/studio.html) for development. Development with Eclipse is currently not possible because we are using the new [project structure](http://developer.android.com/sdk/installing/studio-tips.html).
Spongy Castle is the stock Bouncy Castle libraries with a couple of small changes to make it work on Android. OpenKeychain uses a forked version with some small changes. These changes will been sent to Bouncy Castle, and Spongy Castle will be used again when they have filtered down.
We try to make our builds as [reproducible/deterministic](https://blog.torproject.org/blog/deterministic-builds-part-one-cyberwar-and-global-compromise) as possible.
* Always use a fixed Android Gradle plugin version not a dynamic one, e.g. ``0.7.3`` instead of ``0.7.+`` (allows offline builds without lookups for new versions, also some minor Android plugin versions had serious issues, i.e. [0.7.2 and 0.8.1](http://tools.android.com/tech-docs/new-build-system))
* run ./gradlew wrapper twice to update gradle and download the new gradle jar file
* commit the corresponding [Gradle wrapper](http://www.gradle.org/docs/current/userguide/gradle_wrapper.html) to the repository (allows easy building for new contributors without the need to install the required Gradle version using a package manager)
#### Update SDK and Build Tools
* Open build.gradle and change:
```
ext {
compileSdkVersion = 21
buildToolsVersion = '21.1.2'
}
```
* Change SDK and Build Tools in git submodules "openkeychain-api-lib" and "openpgp-api-lib" manually. They should also build on their own without the ext variables.
#### Add new library
* You can add the library as a Maven dependency or as a git submodule (if patches are required) in the "extern" folder.
* If added as a Maven dependency, pin the library using [Gradle Witness](https://github.com/WhisperSystems/gradle-witness) (Do ``./gradlew -q calculateChecksums`` for Trust on First Use)
1. Paste the `tools/checkstyle.xml` file to `~/.AndroidStudioPreview/config/codestyles/`
2. Go to Settings > Code Style > Java, select OpenPgpChecker, as well as Code Style > XML and select OpenPgpChecker again.
3. Start code inspection and see the results by selecting Analyze > Inspect Code from Android-Studio or you can directly run checkstyle via cli with `.tools/checkstyle`. Make sure it's executable first.
1. Paste the `tools/checkstyle.xml` file to `~/Library/Preferences/AndroidStudioPreview/codestyles`
2. Go to Preferences > Code Style > Java, select OpenPgpChecker, as well as Code Style > XML and select OpenPgpChecker again.
3. Start code inspection and see the results by selecting Analyze > Inspect Code from Android-Studio or you can directly run checkstyle via cli with `.tools/checkstyle`. Make sure it's executable first.