decode method

@override List<int> decode(String mnemonic)

Decodes an Electrum V2 mnemonic string into entropy bytes. -mnemonic: The Electrum V2 mnemonic to decode into entropy bytes.

Implementation

@override
List<int> decode(String mnemonic) {
  /// Parse the mnemonic string
  final mnemonicObj = ElectrumV2Mnemonic.fromString(mnemonic);
  final wCount = mnemonicObj.wordsCount();
  ElectrumV2MnemonicConst.mnemonicWordNum.firstWhere(
    (element) => element.value == wCount,
    orElse:
        () =>
            throw ArgumentException.invalidOperationArguments(
              "decode",
              name: "mnemonic",
              reason: "Invalid mnemonic length.",
            ),
  );

  /// Check the validity of the mnemonic for the specified mnemonic type
  if (!ElectrumV2MnemonicUtils.isValidMnemonic(mnemonicObj, mnemonicType)) {
    throw ArgumentException.invalidOperationArguments(
      "decode",
      name: "mnemonic",
      reason: "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).$1;

  /// 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);
}