License: MIT codecov CI pub package

dart-bip39-mnemonic

Mnemonic code for generating deterministic keys a.k.a. BIP39

Getting started

dart pub add bip39_mnemonic

Features

Usage

Please take a look at the examples in the folder example

Generate a Mnemonic

  // Constructs Mnemonic from random secure 256bits entropy with optional passphrase
  final mnemonic = Mnemonic.generate(
    Language.french,
    passphrase: "SomethingR0bùst",
    length: MnemonicLength.words24,  // ✅ New enum-based parameter
  );
  print(mnemonic.sentence);
  // million alpaga revivre calmer dogme verdure capsule folie déborder facette lanceur saboter recycler tripler symbole savant rieur jeudi outrager volume situer jardin civil reculer
  String hexSeed = hex.encode(mnemonic.seed); // convert to hex
  print(hexSeed);

Construct a Mnemonic from Words

  // Generate a mnemonic from words with English as default language
  List<String> words = [
    'raise',
    'beach',
    'verb',
    'shell',
    'soft',
    'tumble',
    'satoshi',
    'wink',
    'clown',
    'enjoy',
    'more',
    'senior'
  ];
  // You can also specify the language and the passphrase in the named parameters
  final mnemonic2 = Mnemonic.fromWords(words: words);
  print(hex.encode(mnemonic2.seed));

Find the possible last words of an incomplete Sentence

  // Pass the whole sentence but its last word: 11, 14, 17, 20 or 23 words.
  List<String> incomplete = words.sublist(0, 11);
  List<String> candidates = Mnemonic.lastWordCandidates(words: incomplete);
  print(candidates.length);
  // 128
  print(candidates.take(5).toList());
  // [absorb, add, agent, allow, answer]

The last word holds the CS checksum bits preceded by the 11 - CS trailing bits of the entropy, so exactly 2^(11 - CS) words are valid. Candidates are derived from the checksum instead of being searched among the 2048 words, so the cost is one SHA256 per returned word.

sentence valid last words
12 words 128
15 words 64
18 words 32
21 words 16
24 words 8

Construct a Mnemonic from Entropy bytes

  // Constructs a Mnemonic from Entropy bytes
  String hexEntropy =
      "677765ded2b5f05fd11d9bcc38b863fda3fa06475c77bf1e99a668af355b96e2";
  List<int> bytesEntropy = hex.decode(hexEntropy);

  final mnemonic3 = Mnemonic(bytesEntropy, Language.english);
  print(mnemonic3.sentence);
  // guess robot jeans pistol gallery copper dutch recall slow shift body win distance add buddy moment sample visit hat spend viable punch fortune faith

Construct a Mnemonic from a Sentence

  // Constructs a Mnemonic from a Sentence/Phrase
  String frenchSentence =
      "image juteux calculer billard valise billard tortue besace peigne corbeau adroit littoral";
      
  final mnemonic4 = Mnemonic.fromSentence(frenchSentence, Language.french);
  print(hex.encode(mnemonic4.entropy));
  // 7e71249c8ebf603afb68e1b4c6fc18c8
  print(hex.encode(mnemonic4.seed));
  // ad926f1f185ba7745f2c98733a83e51717a58ec83ef52c5cd12048aa8fbe4b2511cf12c2a514d2886510f7020b8a0c1c75bedacfbb3b34cd2f3d8d2c038d531e

Helpers to check words are BIP39 compatible

import 'package:bip39_mnemonic/bip39_mnemonic.dart';
import 'package:convert/convert.dart'; // convert bytes to hexadecimal and vice-versa

void main() {
  // Check if a word is BIP39 compatible for a specific language
  print(Language.english.isValid('baguette')); // false

  // NFKD word formatting is mandatory in BIP39, please take care: https://github.com/flutter/flutter/issues/104927#issuecomment-1141140735
  final french = Language.french;
  String nonNfkd = 'échelle';
  String nfkd = 'échelle';
  print(french.isValid(nfkd)); // true
  print(french.isValid(nonNfkd)); // true, because isValid formats input
}

Libraries

bip39_mnemonic