decode method

@override List<int> decode(String mnemonic)

Decodes an Electrum V2 mnemonic string into entropy bytes.

This method takes an Electrum V2 mnemonic string as input and decodes it into entropy bytes. It performs several checks to ensure the validity of the mnemonic, including verifying the word count, checking if the mnemonic is valid for the specified mnemonic type, and detecting the language if it was not specified during construction.

mnemonic: The Electrum V2 mnemonic to decode into entropy bytes. Returns a List

Implementation

@override
List<int> decode(String mnemonic) {
  /// Parse the mnemonic string
  final mnemonicObj = ElectrumV2Mnemonic.fromString(mnemonic);
  final wCount = mnemonicObj.wordsCount();

  /// Check if the word count matches a valid Electrum V2 word count
  try {
    ElectrumV2MnemonicConst.mnemonicWordNum
        .firstWhere((element) => element.value == wCount);
  } on StateError {
    throw ArgumentException('Mnemonic words count is not valid ($wCount)');
  }

  /// Check the validity of the mnemonic for the specified mnemonic type
  if (!ElectrumV2MnemonicUtils.isValidMnemonic(mnemonicObj, mnemonicType)) {
    throw const ArgumentException('Invalid mnemonic');
  }

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

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

  /// Decode the words into entropy as a BigInt
  final n = BigInt.from(wordsList.length());
  BigInt entropyInt = BigInt.zero;
  for (final word in words.reversed) {
    entropyInt = (entropyInt * n) + BigInt.from(wordsList.getWordIdx(word));
  }

  /// Convert the BigInt to bytes and return the result
  return BigintUtils.toBytes(entropyInt,
      length: BigintUtils.orderLen(entropyInt));
}