https://github.com/novacrypto/bip39
Java Microlibrary implementation of BIP0039
https://github.com/novacrypto/bip39
bip39 bitcoin ethereum litecoin mnemonic
Last synced: 2 months ago
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Java Microlibrary implementation of BIP0039
- Host: GitHub
- URL: https://github.com/novacrypto/bip39
- Owner: NovaCrypto
- License: gpl-3.0
- Created: 2017-10-08T15:02:10.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2021-11-06T23:06:00.000Z (almost 4 years ago)
- Last Synced: 2023-02-27T17:41:54.482Z (over 2 years ago)
- Topics: bip39, bitcoin, ethereum, litecoin, mnemonic
- Language: Java
- Homepage: https://novacrypto.github.io/BIP39
- Size: 282 KB
- Stars: 92
- Watchers: 6
- Forks: 37
- Open Issues: 7
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
[](https://bintray.com/novacrypto/BIP/BIP39/_latestVersion) [](https://travis-ci.org/NovaCrypto/BIP39) [](https://codecov.io/gh/NovaCrypto/BIP39)
Read all about how I wrote this and understanding BIP39 [here](https://medium.com/@_west_on/coding-a-bip39-microlibrary-in-java-bb90c1109123).
Apart from generating a seed, only English, French, Spanish and Japanese [currently packaged](https://github.com/NovaCrypto/BIP39/issues/1), but as `WordList` is an interface and you can provide your own.
# Install
Use either of these repositories:
```
repositories {
jcenter()
}
```
Or:
```
repositories {
maven {
url 'https://dl.bintray.com/novacrypto/BIP/'
}
}
```
Add dependency:
```
dependencies {
compile 'io.github.novacrypto:BIP39:2019.01.27'
}
```
# Usage
## Generate a mnemonic
Using a `StringBuilder`:
```
StringBuilder sb = new StringBuilder();
byte[] entropy = new byte[Words.TWELVE.byteLength()];
new SecureRandom().nextBytes(entropy);
new MnemonicGenerator(English.INSTANCE)
.createMnemonic(entropy, sb::append);
System.out.println(sb.toString());
```
If you're paranoid and/or need higher than normal [memory security](https://medium.com/@_west_on/protecting-strings-in-jvm-memory-84c365f8f01c), consider using a [`SecureCharBuffer`](https://github.com/NovaCrypto/SecureString):
```
try (SecureCharBuffer secure = new SecureCharBuffer()) {
byte[] entropy = new byte[Words.TWELVE.byteLength()];
new SecureRandom().nextBytes(entropy);
new MnemonicGenerator(English.INSTANCE)
.createMnemonic(entropy, secure::append);
Arrays.fill(entropy, (byte) 0); //empty entropy
//do something with your secure mnemonic
}
```
## Validate a mnemonic
```
try {
MnemonicValidator
.ofWordList(English.INSTANCE)
.validate(mnemonic);
} catch (UnexpectedWhiteSpaceException e) {
...
} catch (InvalidWordCountException e) {
...
} catch (InvalidChecksumException e) {
...
} catch (WordNotFoundException e) {
...
//e.getSuggestion1()
//e.getSuggestion2()
}
```
Or if you have a list of words from a word list:
```
MnemonicValidator
.ofWordList(English.INSTANCE)
.validate(mnemonicWordsInAList);
```
## Generate a seed
As does not use a word list, can be used now for any language.
```
byte[] seed = new SeedCalculator().calculateSeed(mnemonic, passphrase);
```
Or if you have a list of words from a word list:
```
byte[] seed = new SeedCalculator()
.withWordsFromWordList(English.INSTANCE)
.calculateSeed(mnemonicWordsInAList, passphrase);
```
Note: it will work for words off of the word list, but it allows use of secure CharSequences if they match the wordlist, normalized or not (as they are never `toString`ed)
Those examples both use SpongyCastle, if you don't need or want that dependency, you can use `javax.crypto` like so:
```
byte[] seed = new SeedCalculator(JavaxPBKDF2WithHmacSHA512.INSTANCE).calculateSeed(mnemonic, passphrase);
```
That will not work on Android API < 26 https://developer.android.com/reference/javax/crypto/SecretKeyFactory.html and see Issue #17.