Flutter + Ethereum BIP39, BIP32

OKAddress.dart

import 'package:bip39/bip39.dart' as bip39;
import "package:hex/hex.dart";
import 'package:web3dart/credentials.dart';
import 'package:bip32/bip32.dart' as bip32;

abstract class OKAddressETH {  
  String generateMnemonic();  
  String getPrivateKey(String mnemonic);  
  Future<EthereumAddress> getPublicAddress(String privateKey);            
}

class OKAddress implements OKAddressETH {
 @override  
 String generateMnemonic() {
    return bip39.generateMnemonic();
 }
 @override  
 String getPrivateKey(String mnemonic) {
    final privateKey = HEX.encode(master.key);
    final root = bip32.BIP32.fromSeed(HEX.decode(seed));
    final child1 = root.derivePath("m/44'/60'/0'/0/0");
    final privateKey = HEX.encode(child1.privateKey); 
       
    return privateKey;  
 }
 @override  
 Future<EthereumAddress> getPublicAddress(String privateKey) async {
    final private = EthPrivateKey.fromHex(privateKey);
    final address = await private.extractAddress();    
    return address;  
 }
}