Language Bindings for BDK

The code in this repository creates a library ready for export to other languages using uniffi-rs for the Rust-based bdk_wallet library from the Bitcoin Dev Kit project.

Each supported language (Kotlin for Android and Swift for iOS) and the platforms it's packaged for has its own directory. The Rust code in this project is in the bdk-ffi directory and is a wrapper around the bdk_wallet library to expose its APIs in a uniform way using the mozilla/uniffi-rs bindings generator for each supported target language.

Supported target languages and platforms

The below directories include instructions for building and using the language binding for bdk_wallet supported by this project.

Language	Platform	Published Package	Building Documentation	API Docs
Kotlin	Android	bdk-android	Readme bdk-android	Android API Docs
Swift	iOS, macOS	bdk-swift	Readme bdk-swift

Other supported languages maintained in separate repositories

The bdk-ffi codebase in this repository can be used to produce language bindings for more than Swift and Kotlin. Some of these require the use of uniffi 3rd party plugins and some not. Below are some of the libraries that use the bdk-ffi API, but are maintained separately. Refer to their individual READMEs for information on their state of production-readiness.

Language	Platform	Published Package	Repository	API Docs
Kotlin	JVM	bdk-jvm (Maven Central)	bdk-jvm
Python	Linux, macOS, Windows	bdk-python (PyPI)	bdk-python

Building and testing the libraries

If you are familiar with the build tools for the specific languages you wish to build the libraries for, you can use their normal build/test workflows. We also include some just files to simplify the work across different languages. If you have the just tool installed on your system, you can simply call the commands defined in the justfiles, for example:

cd bdk-android
just build
just test
just publish-local

Contributing

To add new structs and functions, see the UniFFI User Guide and the uniffi-examples repository.

Goals

1. Language bindings should feel idiomatic in target languages/platforms
2. Adding new targets should be easy
3. Getting up and running should be easy
4. Contributing should be easy
5. Get it right, then automate

Verifying Signatures

Both libraries and all their corresponding artifacts are signed with a PGP key you can find in the root of this repository. To verify the signatures follow the below steps:

1. Import the PGP key in your keyring.

# Navigate to the root of the repository and import the ./PGP-BDK-BINDINGS.asc public key
gpg --import ./PGP-BDK-BINDINGS.asc
    
# Alternatively, you can import the key directly from a public key server
gpg --keyserver keyserver.ubuntu.com --receive-key 2768C43E8803C6A3
    
# Verify that the correct key was imported
gpg --list-keys
# You should see the below output
pub   ed25519 2022-08-31 [SC]
    88AD93AC4589FD090FF3B8D12768C43E8803C6A3
uid           [ unknown] bitcoindevkit-bindings <bindings@bitcoindevkit.org>
sub   cv25519 2022-08-31 [E]

2. Download the binary artifacts and corresponding signature files.

• from bdk-jvm
  • bdk-jvm-<version>.jar
  • bdk-jvm-<version>.jar.asc
• from bdk-android
  • bdk-android-<version>.aar
  • bdk-android-<version>.aar.asc

3. Verify the signatures.

gpg --verify bdk-jvm-<version>.jar.asc 
gpg --verify bdk-android-<version>.aar.asc

# you should see a "Good signature" result
gpg: Good signature from "bitcoindevkit-bindings <bindings@bitcoindevkit.org>" [unknown]

PGP Metadata

Full key ID: 88AD 93AC 4589 FD09 0FF3 B8D1 2768 C43E 8803 C6A3
Fingerprint: 2768C43E8803C6A3
Name: bitcoindevkit-bindings
Email: bindings@bitcoindevkit.org

Thanks

This project is made possible thanks to the wonderful work by the mozilla/uniffi-rs team.