First Signing Flow

Minimal Flutter signing pipeline:

1. Resolve sender address
2. Calculate fees
3. Build pre-image
4. Sign

Example

import 'package:blockchain_kit_sdk_flutter_plugin/blockchain_kit_sdk_flutter_plugin.dart';

final sdk = BlockchainKitSdk();
const groupId = 'YOUR_GROUP_ID';

final network = Network(
  'ethereum-mainnet',
  'Ethereum Mainnet',
  NetworkType.EVM,
  BigInt.from(1),
  RpcConfig('https://rpc.ankr.com/eth'),
  EvmFeatures(true, true, true, true, false),
  null,
  null,
  null,
  NativeCurrency('Ether', 'ETH', 18),
  Explorer('https://etherscan.io/tx/', 'https://etherscan.io/address/'),
);

final asset = NativeCoin(network, null);

// 1) Address
final addressResult = await sdk.blockchainService.getAddress(asset, groupId);

await addressResult.fold((fromAddress) async {
  // 2) Build transaction intent
  final tx = Transfer(
    asset,
    BigInt.from(1000000000000000), // 0.001 ETH in wei
    '0x1111111111111111111111111111111111111111',
    false,
    null,
  );

  // 3) Fees
  final feeResult = await sdk.blockchainService.calculateFees(tx, fromAddress);
  await feeResult.fold((fee) async {
    // 4) Pre-image + sign
    final preImageResult = await sdk.blockchainService.preImageHash(tx, fromAddress, fee);
    await preImageResult.fold((preImage) async {
      final signResult = await sdk.blockchainService.sign(preImage, groupId);
      signResult.fold(
        (signedTxHex) => print('Signed tx hex: $signedTxHex'),
        (error) => print('Sign failed: ${error.message}'),
      );
    }, (error) async {
      print('Pre-image failed: ${error.message}');
    });
  }, (error) async {
    print('Fee calc failed: ${error.message}');
  });
}, (error) async {
  print('Address resolution failed: ${error.message}');
});

Notes

• This example signs but does not broadcast.
• To broadcast, call sdk.blockchainService.sendTransaction(network, signedTxHex).