mnemonic4j

Java implementation of BIP-0039: Mnemonic code for generating deterministic keys.

Overview

This library provides an implementation of the Bitcoin BIP-0039 specification for generating mnemonic sentences and converting them into binary seeds. The generated seeds can be used to create deterministic wallets using BIP-0032 or similar methods.

Installation

To use this library in your Java project, add the following dependency to your pom.xml file:

<dependency>
    <groupId>network.lightsail</groupId>
    <artifactId>mnemonic4j</artifactId>
    <version>0.1.1</version>
</dependency>

If you are using Gradle, add the following dependency to your build.gradle file:

dependencies {
    implementation("network.lightsail:mnemonic4j:0.1.1")
}

Documentation

Full documentation for this library can be found on:

• Javadoc
• GitHub Pages (latest release)

Usage

Generating Mnemonic Sentence

To generate a mnemonic sentence, create an instance of the Mnemonic class and call the generate method, specifying the desired strength (128 - 256):

Mnemonic mnemonic = new Mnemonic();
String words = mnemonic.generate();

Converting Mnemonic to Seed

To convert a mnemonic sentence into a binary seed, use the toSeed method:

String words = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about";
String passphrase = "passw0rd";
Mnemonic mnemonic = new Mnemonic();
byte[] seed = Mnemonic.toSeed(words, passphrase);

Checking Mnemonic Validity

To check if a mnemonic sentence is valid, use the check method:

String words = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about";
boolean valid = new Mnemonic().check(words);

Retrieving Original Entropy

To retrieve the original entropy from a mnemonic sentence, use the toEntropy method:

Mnemonic mnemonic = new Mnemonic();
byte[] entropy = mnemonic.toEntropy(words);

Multiple Languages and custom word lists support

The library supports multiple languages and custom word lists. To generate a mnemonic sentence in a specific language, use the Language enum:

Mnemonic mnemonic = new Mnemonic(Language.CHINESE_SIMPLIFIED, null);
String words = mnemonic.generate();

To use a custom word list, pass the list of words as a List<String> to the Mnemonic constructor:

List<String> customWords = Arrays.asList("word0", "word2", "word3", ...);
Mnemonic mnemonic = new Mnemonic(Language.ENGLISH, customWords);
String words = mnemonic.generate();

Android Support

The library works well on Android platforms:

• For Android platforms with API level 26 and above, no additional configuration is required.

• For versions below Android API 26, due to the lack of support for certain necessary cryptographic algorithms, you need to include the following dependency:

  implementation("org.bouncycastle:bcprov-jdk18on:1.78.1")

  Additionally, add the following lines of code to your Android project:

  Security.removeProvider(BouncyCastleProvider.PROVIDER_NAME)
  Security.addProvider(BouncyCastleProvider() as Provider?)

License

This library is released under the Apache 2.0 License.

Acknowledgements

This project was inspired by and builds upon the excellent work done in the trezor/python-mnemonic project.