How to recover private key of web3 wallet?

[anjalialance]

Hello, I am creating wallet using web3 web3js.eth.accounts.create(); for mnemonics. I am unable to recover the same private key for the same mnemonics. I tried hdkey but unable to proceed transaction. I also used extended private key derived from hdkey but unable to proceed transaction. Please guide me.

Thanks in advance.

`app.get('/send_tx', (req, res,err) => {

var myAddress = '0x6486b5073Ab7EFe3741acE325295B31556686c3f';

//this private key is from mnemonics using hdkey package
var privateKey = Buffer.from('xprv9s21ZrQH143K4YTuEb1TZ6uxTNCGz9GZNEexbPn2rTWLciD9j6amMVaLSACgFHjeAdom7X5r9FCHykvMJUiiHfSxjPV928Uyq8dUdsnVaEw', 'hex');

const wal = HDKey.fromExtendedKey(privateKey);
const w = wal.deriveChild(0).getWallet();

const childPK = w.getPrivateKey();

console.log(childPK);

var toAddress = '0xb2cB609010ac2cDA463758ce0B6f420AbDeDC0ee';

var contractABI ="[{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"name":"approve","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"version","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"},{"name":"_extraData","type":"bytes"}],"name":"approveAndCall","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"payable":false,"stateMutability":"nonpayable","type":"fallback"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_from","type":"address"},{"indexed":true,"name":"_to","type":"address"},{"indexed":false,"name":"_value","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_owner","type":"address"},{"indexed":true,"name":"_spender","type":"address"},{"indexed":false,"name":"_value","type":"uint256"}],"name":"Approval","type":"event"}]"

const user = JSON.parse(contractABI);

var contractAddress = '0x9Bd3F09eda3aF694373faF154Bc74ebEb62d3d42';
var contract = new web3js.eth.Contract(user,contractAddress);
var count;
web3js.eth.getTransactionCount(myAddress).then(function(v){
console.log("Count: "+v);

count = v;

var amount = web3js.utils.toHex(1);

var rawTransaction = {
nonce: web3js.utils.toHex(count),
to: toAddress,
value: web3js.utils.toHex(web3js.utils.toWei('0.001', 'ether')),
gasLimit: web3js.utils.toHex(21000),
gasPrice: web3js.utils.toHex(web3js.utils.toWei('10', 'gwei')),
}
console.log(rawTransaction);

var transaction = new Tx(rawTransaction);

transaction.sign(childPK);

web3js.eth.sendSignedTransaction('0x'+transaction.serialize().toString('hex'),(err,hash)=>{

         if(hash){
              let student = {  
                status:1,
                txhash: hash,

            };let data = JSON.stringify(student);  
                 res.send(data);
            }else if(err){
              
               let student1 = {  
                status:0,
                message:err,

            };let data1 = JSON.stringify(student1);  
                 res.send(data1);
              
              
                // res.send("somethings went wrong");
                // console.log(Error.error);
                 console.log(err);

            }
       
         //web3js.eth.getTransaction(hash)
       
    })
         .on('transactionHash');

          web3js.eth.getTransactionCount(myAddress,console.log)

  });

});`

[dev1644]

web3js.eth.accounts.create() doesn't give you a mnemonic sequence, instead it gives a wallet object.
This wallet object contains -:

• Address/PrivateKey - Keypair.
• signTransaction - Function to sign your transaction with Wallet's private key.
• sign - Function to sign your message with Wallet's private key.
• encrypt - Function to sign your data with Wallet's private key.

[anjalialance]

Hii,

Thanks for reply.

I am getting Address/Privatekey using web3js.eth.accounts.create() for mnemonic.But I want same private key again for transaction as i do not want to save the private key in my db.

[dev1644]

web3js.eth.accounts.create() give you a newly generated Wallet each time.
If you don't want to save private keys into Database and derive it the runtime use following steps -:

• Generate a seed from your mnemonic sequence bip39.mnemonicToSeed('Your Mnemonic Sequence').
• Get your HDkey by HDKey.fromMasterSeed(new Buffer(seed, 'hex')) .
• Set path for getting multiple deterministic key pairs ethPath = m/44'/60'/0'/0/${Your Unique Number}& fetch private-key from this path_ethkey = eth.derive(ethPath)`.
• Use web3 library to convert your private-key into wallet, web3.eth.accounts.privateKeyToAccount(_ethkey._privateKey)
• You will have your runtime wallet object, that you can use it.

[nivida]

Closed this issue because the issue template was not used.

[italoHonoratoSA]

Web3.js is much more complicated when it comes to handling accounts and extracting private keys through mnemonic.

Check my reviews here:
#1594 (comment)

Check a solution here:
https://ethereum.stackexchange.com/questions/102090/retrieving-the-private-public-key-with-web3js-for-a-specific-wallet-provided-by