signOffChain static method

String signOffChain(EthPrivateKey credentials, String from, String to, String data, String nonce, { BigInt? value, BigInt? gasPrice, BigInt? gasLimit, })

Signs an off-chain transaction using the provided credentials and transaction data.

credentials is the private key used for signing. from is the address of the sender. to is the address of the receiver. data is the transaction data to be sent. nonce is the nonce of the transaction. value is the optional amount of Ether to be sent. gasPrice is the optional gas price for the transaction. gasLimit is the optional gas limit for the transaction.

Returns a hex string representing the signed transaction.

Implementation

static String signOffChain(
  EthPrivateKey credentials,
  String from,
  String to,
  String data,
  String nonce, {
  BigInt? value,
  BigInt? gasPrice,
  BigInt? gasLimit,
}) {
  final List<String> inputArr = [
    '0x19',
    '0x00',
    from,
    to,
    hexZeroPad(hexlify(value ?? BigInt.from(0)), 32),
    data,
    nonce,
    hexZeroPad(hexlify(gasPrice ?? BigInt.from(0)), 32),
    hexZeroPad(
        hexlify(gasLimit ?? BigInt.from(Variables.DEFAULT_GAS_LIMIT)), 32)
  ];
  final String input =
      '0x${inputArr.map((hexStr) => hexStr.toString().substring(2)).join('')}';
  final Uint8List messagePayload = keccak256(hexToBytes(input));
  final Uint8List signature = credentials.signPersonalMessageToUint8List(
    messagePayload,
  );
  return bytesToHex(signature, include0x: true);
}