bdk-kotlin

⚠️⚠️ The code in this repository has been moved to bdk-ffi, and development is continuing there. This repository is now considered an archive, and will not accept new pull requests or issues. ⚠️⚠️

This project builds .jar and .aar packages for the jvm and android platforms that provide Kotlin language bindings for the bdk library. The Kotlin language bindings are created by the bdk-ffi project which is included as a git submodule of this repository.

How to Use

To use the Kotlin language bindings for bdk in your jvm or android project add the following to your gradle dependencies:

repositories {
    mavenCentral()
}

dependencies {
  
  // for jvm
  implementation 'org.bitcoindevkit:bdk-jvm:<version>'
  // OR for android
  implementation 'org.bitcoindevkit:bdk-android:<version>'
  
}

You may then import and use the org.bitcoindevkit library in your Kotlin code. For example:

import org.bitcoindevkit.*

// ...

val externalDescriptor = "wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/0/*)"
val internalDescriptor = "wpkh([c258d2e4/84h/1h/0h]tpubDDYkZojQFQjht8Tm4jsS3iuEmKjTiEGjG6KnuFNKKJb5A6ZUCUZKdvLdSDWofKi4ToRCwb9poe1XdqfUnP4jaJjCB2Zwv11ZLgSbnZSNecE/1/*)"

val databaseConfig = DatabaseConfig.Memory

val blockchainConfig =
  BlockchainConfig.Electrum(
    ElectrumConfig("ssl://electrum.blockstream.info:60002", null, 5u, null, 10u)
  )
val wallet = Wallet(externalDescriptor, internalDescriptor, Network.TESTNET, databaseConfig, blockchainConfig)
val newAddress = wallet.getNewAddress()

Example Projects

bdk-android

• Devkit Wallet
• Padawan Wallet

bdk-jvm

• Tatooine Faucet

How to build

Note that Kotlin version 1.6.10 or later is required to build the library.

1. Clone this repository and initialize and update its bdk-ffi submodule.

git clone https://github.com/bitcoindevkit/bdk-kotlin
git submodule update --init

2. Follow the "General" bdk-ffi "Getting Started (Developer)" instructions.
3. If building on MacOS install required intel and m1 jvm targets

rustup target add x86_64-apple-darwin aarch64-apple-darwin

4. Install required targets

rustup target add x86_64-linux-android aarch64-linux-android armv7-linux-androideabi

5. Install Android SDK and Build-Tools for API level 30+
6. Setup $ANDROID_SDK_ROOT and $ANDROID_NDK_ROOT path variables (which are required by the build tool), for example (NDK major version 21 is required):

export ANDROID_SDK_ROOT=~/Android/Sdk
export ANDROID_NDK_ROOT=$ANDROID_SDK_ROOT/ndk/21.<NDK_VERSION>

7. Build kotlin bindings

# build JVM library
cd bdk-jvm
./gradlew buildJvmLib

# build Android library
cd bdk-android
./gradlew buildAndroidLib

8. Start android emulator (must be x86_64) and run tests

./gradlew connectedAndroidTest 

How to publish

Publish to your local maven repo

# bdk-jvm
cd bdk-jvm
./gradlew publishToMavenLocal --exclude-task signMavenPublication

# bdk-android
cd bdk-android
./gradlew publishToMavenLocal --exclude-task signMavenPublication

Note that the commands assume you don't need the local libraries to be signed. If you do wish to sign them, simply set your ~/.gradle/gradle.properties signing key values like so:

signing.gnupg.keyName=<YOUR_GNUPG_ID>
signing.gnupg.passphrase=<YOUR_GNUPG_PASSPHRASE>

and use the publishToMavenLocal task without excluding the signing task:

./gradlew publishToMavenLocal

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 <[email protected]>
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 <[email protected]>" [unknown]

PGP Metadata

Full key ID: 88AD 93AC 4589 FD09 0FF3 B8D1 2768 C43E 8803 C6A3
Fingerprint: 2768C43E8803C6A3
Name: bitcoindevkit-bindings
Email: [email protected]