signTransaction gives 'Must provide "signTransaction" fn in constructor option' error

[ArvsIndrarys]

For my project, I need to do some offline transaction signing, before sending the result to the backend, which will send them. But I am encountering the following error :

Error: Error: ProviderEngine - HookedWalletSubprovider - Must provide "signTransaction" fn in constructor options
    at HookedWalletSubprovider.signTransaction (chrome-extension://nkbihfbeogaeaoehlefnkodbefgpgknn/background.js:18092)
    at t (chrome-extension://nkbihfbeogaeaoehlefnkodbefgpgknn/background.js:486)
    at u (chrome-extension://nkbihfbeogaeaoehlefnkodbefgpgknn/background.js:486)
    at chrome-extension://nkbihfbeogaeaoehlefnkodbefgpgknn/background.js:456
    at chrome-extension://nkbihfbeogaeaoehlefnkodbefgpgknn/background.js:18092
    at chrome-extension://nkbihfbeogaeaoehlefnkodbefgpgknn/background.js:459
...

I currently have :

> web3.version
{api: "0.20.3", getNode: ƒ, getNetwork: ƒ, …}

And I saw it in : https://github.com/ethereum/web3.js/blob/6d3e61a010501011a107a79574cc7516900fa9e4/lib/web3/methods/eth.js#L205
and (outdated) : https://web3js.readthedocs.io/en/1.0/web3-eth.html#signtransaction

I am clueless about how to resolve it as it don't seem to be due to my code... Can somebody help?

[ArvsIndrarys]

I am using Metamask, which use Infura, for testing my app, so I am almost sure it isn't an ethereum client problem.

[jetpack3331]

@ArvsIndrarys I have signTransaction implemented like this:

signTransaction: async (txParams, cb) => {
// Fetch private key as u want
const res = await wallets.fetchPrivateKey(txParams.from);
const privateKey = typeof res.result !== 'undefined' ? res.result : res;
const gasPrice = await web3.eth.getGasPrice();

const txObject = {
  from: txParams.from,
  to: txParams.to,
  data: txParams.data,
  gasPrice: web3.utils.toHex(gasPrice),
  gasLimit: web3.utils.toHex(gasLimit),
  value: '0x00',
  nonce: txParams.nonce,
  chainId: <NETWORKID>, // see: https://ethereum.stackexchange.com/questions/17051/how-to-select-a-network-id-or-is-there-a-list-of-network-ids
};

const tx = new Tx(txObject);
tx.sign(Buffer.from(privateKey, 'hex'));
try {
  const serialized = tx.serialize();
  cb(null, `0x${serialized.toString('hex')}`);
} catch (error) {
  console.log({ error });
}

}

[ArvsIndrarys]

As my code would be expected to go to production and of public use, I won't accept extracting the private key because of security breach.
This method would extract and use Metamask under the hood without giving access to this key.

[jetpack3331]

@ArvsIndrarys of course, but if you can't use MetaMask or Ledger or something and u have your own methods tosigning, there is probably no other way. Ofc better is to have it on API hidden from browser

[ArvsIndrarys]

Any other methods require private key extraction, so I had to use the sendTransaction() method.
I would have appreciated signing from the front-end and execute the transaction from my backend (web3J).

It seems I finally did it few days ago, using a little reverse-engineering and the sign() method, giving the transaction then extracting the r,s and v parameters ( https://github.com/ethereum/wiki/wiki/JavaScript-API#web3ethsign ) and computing the result so as it looked like the signed Transaction given in the https://web3js.readthedocs.io/en/1.0/web3-eth.html#signtransaction example.

But as web3js and web3J don't sign the same way ( hyperledger/web3j#208 ) and I was never able to send the signed transaction from the backend :/ .
And from the logging, I couldn't determined if it was because my way was not working, or if it was due to the signing differences.

May I ask why the signTransaction() method was abandoned ?

[jetpack3331]

@ArvsIndrarys It wasnt abandoned.
https://github.com/ethereum/wiki/wiki/JavaScript-API#web3ethsign is documentation for 0.2x.x

In version 1.0.0 there is signTransaction method

[ArvsIndrarys]

My bad, I don't know know about my first problem then... Must provide "signTransaction" fn in constructor options is obscure to me

[nivida]

Version 0.20.x got his last maintenance release with v0.20.7. Please update your code to the latest 1.0 version of Web3.js. Further details about the current project state are explained in the release announcement of version 1.0.0-beta.38.