Signing

Learn how to sign messages and transactions in your Flutter app using Turnkey’s Embedded Wallets.

Overview

Turnkey’s Flutter SDK makes it simple to sign messages and transactions using embedded wallets managed by the TurnkeyProvider.

Signing messages

To sign a message, select a wallet account and call signMessage from the TurnkeyProvider. You can optionally pass in the payload’s encoding and hashFunction if needed.

lib/widgets/sign_message_button.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:turnkey_sdk_flutter/turnkey_sdk_flutter.dart';

class SignMessageButton extends StatelessWidget {
  const SignMessageButton({super.key});

  @override
  Widget build(BuildContext context) {
    final tk = Provider.of<TurnkeyProvider>(context, listen: false);

    Future<void> doSignMessage() async {
      try {
        final wallet = tk.wallets?.first;
        final account = wallet?.accounts.first;


        final message = 'Hello, Turnkey!';
        final signature = await tk.signMessage(
          walletAccount: account,
          message: message,
        );

        debugPrint('Message signature: $signature');
      } catch (e) {
        debugPrint('Sign message failed: $e');
      }
    }

    return ElevatedButton(
      onPressed: doSignMessage,
      child: const Text('Sign Message'),
    );
  }
}

Signing transactions

To sign transactions, use the signTransaction function. Select a wallet account’s address, prepare an unsigned transaction, and specify a transaction type.

lib/widgets/sign_transaction_button.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:turnkey_sdk_flutter/turnkey_sdk_flutter.dart';

class SignTransactionButton extends StatelessWidget {
  const SignTransactionButton({super.key});

  @override
  Widget build(BuildContext context) {
    final tk = Provider.of<TurnkeyProvider>(context, listen: false);

    Future<void> doSignTransaction() async {
      try {
        final wallet = tk.wallets?.first;
        final account = wallet?.accounts.first;

        final unsignedTx = '0x...'; // unsigned transaction hex
        final signature = await tk.signTransaction(
          signWith: account.address,    // use the address of the wallet account
          unsignedTransaction: unsignedTx,
          transactionType: v1TransactionType.transaction_type_ethereum,
        );

        debugPrint('Tx signature: $signature');
      } catch (e) {
        debugPrint('Sign transaction failed: $e');
      }
    }

    return ElevatedButton(
      onPressed: doSignTransaction,
      child: const Text('Sign Transaction'),
    );
  }
}