sign method
Signs the given message
using the private key and returns the signature as a hexadecimal string.
message
is the message to be signed.
Implementation
String sign(String message) {
final signer = XrpSigner.fromKeyBytes(toBytes(), algorithm.curveType);
final sign = signer.sign(BytesUtils.fromHexString(message));
return BytesUtils.toHexString(sign);
}