decode method

@override List<int> decode(String mnemonic)

Decodes an Electrum V1 mnemonic string into a List

This method takes an Electrum V1 mnemonic string as input and processes it to obtain the corresponding entropy bytes. It validates the mnemonic's word count and detects the language if it was not specified during construction. Then, it converts the mnemonic words into entropy bytes by considering 3 words at a time, where 3 words represent 4 bytes.

Throws an ArgumentException if the mnemonic words count is not valid.

Returns a List

mnemonic: The Electrum V1 mnemonic string to decode.

Implementation

@override
List<int> decode(String mnemonic) {
  /// Parse the mnemonic into an Electrum V1 mnemonic object
  final mnemonicObj = ElectrumV1Mnemonic.fromString(mnemonic);

  /// Get the number of words in the mnemonic
  final wCount = mnemonicObj.wordsCount();

  /// Validate the words count against a predefined list
  try {
    ElectrumV1MnemonicConst.mnemonicWordNum
        .firstWhere((element) => element.value == wCount);
  } on StateError {
    throw ArgumentException('Mnemonic words count is not valid ($wCount)');
  }

  // Detect language if it was not specified at construction
  final wordsList = findLanguage(mnemonicObj).item1;

  // Get words from the mnemonic
  final words = mnemonicObj.toList();

  // Consider 3 words at a time, 3 words represent 4 bytes
  List<int> entropyBytes = List.empty();
  for (int i = 0; i < words.length ~/ 3; i++) {
    final word1 = words[i * 3];
    final word2 = words[i * 3 + 1];
    final word3 = words[i * 3 + 2];
    entropyBytes = List<int>.from([
      ...entropyBytes,
      ...MnemonicUtils.wordsToBytesChunk(
        word1,
        word2,
        word3,
        wordsList,
      )
    ]);
  }

  return entropyBytes;
}