[Ethereum] How to recover the address from message and signature generated with web3.personal.sign

ethereumjsnodejsweb3js

Is there any way to do that? To recover address in nodejs server-side from signature and message after it was signed with web3.personal.sign client-side?
I tried this: https://ethereum.stackexchange.com/a/12580/42452 with ethereumjs-util; I tried recoverTypedSignature() from eth-sig-util but in both cases recovered addresses didn't match signing addresses.

Here is the client-side code:

function authorize() {
  web3.eth.getAccounts(function (err, account) {
    let nonce = "123ABC";
    web3.personal.sign(nonce, account[0], function (err, signature) {
      //send to nodejs server
      $.post("http://localhost:8087", {signature: signature, nonce: nonce, address: account[0]}, function (data) {
        console.log(data);
      });
    })
  })
}

and server-side:

app.post('/', cors(corsOptions), function(req, res){
const msg = web3.sha3(nonce);
const sig = signature;
const {v, r, s} = util.fromRpcSig(sig);

const pubKey  = util.ecrecover(util.toBuffer(msg), v, r, s);
const addrBuf = util.pubToAddress(pubKey);
const addr    = util.bufferToHex(addrBuf);

console.log(addr);
});
app.listen(8087);

Best Answer

So, after many hours, I found a solution, that works. To make it works I used method from ethereumjs-util - ecrecover. I had to add some prefixed message to signed nonce. Code looks like this:

function checkSignature(nonce, signature, res) {

  nonce = "\x19Ethereum Signed Message:\n" + nonce.length + nonce;
  nonce = util.keccak(nonce);
  const sig = signature;
  const {v, r, s} = util.fromRpcSig(sig);
  const pubKey  = util.ecrecover(util.toBuffer(nonce), v, r, s);
  const addrBuf = util.pubToAddress(pubKey);
  const addr    = util.bufferToHex(addrBuf);
  console.log(addr);

}

Related Solutions

[Ethereum] Is the signature generated by “web3.personal.sign” different with “web3.eth.sign”

I think I had similar problem. I couldn't get correct address from ecrecover after message was signed with personal.sign, but it works fine after it was sign with eth.sign. Then I found this on web3 docs: https://web3js.readthedocs.io/en/1.0/web3-eth-personal.html#sign

"Signs data using a specific account. This data is before UTF-8 HEX decoded and enveloped as follows: "\x19Ethereum Signed Message:\n" + message.length + message."

After I added "\x19Ethereum Signed Message:\n" and message length to signed message, from which I want to recover address, it finally return correct address.

[Ethereum] Recover address from signature using web3j

package org.web3j.crypto;

import java.math.BigInteger;
import java.util.Arrays;

import org.junit.jupiter.api.Test;

import org.web3j.crypto.Sign.SignatureData;
import org.web3j.utils.Numeric;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

public class ECRecoverTest {

    public static final String PERSONAL_MESSAGE_PREFIX = "\u0019Ethereum Signed Message:\n";

    @Test
    public void testRecoverAddressFromSignature() {

        String signature =
                "0x2c6401216c9031b9a6fb8cbfccab4fcec6c951cdf40e2320108d1856eb532250576865fbcd452bcdc4c57321b619ed7a9cfd38bd973c3e1e0243ac2777fe9d5b1b";

        String address = "0x31b26e43651e9371c88af3d36c14cfd938baf4fd";
        String message = "v0G9u7huK4mJb2K1";

        String prefix = PERSONAL_MESSAGE_PREFIX + message.length();
        byte[] msgHash = Hash.sha3((prefix + message).getBytes());

        byte[] signatureBytes = Numeric.hexStringToByteArray(signature);
        byte v = signatureBytes[64];
        if (v < 27) {
            v += 27;
        }

        SignatureData sd =
                new SignatureData(
                        v,
                        (byte[]) Arrays.copyOfRange(signatureBytes, 0, 32),
                        (byte[]) Arrays.copyOfRange(signatureBytes, 32, 64));

        String addressRecovered = null;
        boolean match = false;

        // Iterate for each possible key to recover
        for (int i = 0; i < 4; i++) {
            BigInteger publicKey =
                    Sign.recoverFromSignature(
                            (byte) i,
                            new ECDSASignature(
                                    new BigInteger(1, sd.getR()), new BigInteger(1, sd.getS())),
                            msgHash);

            if (publicKey != null) {
                addressRecovered = "0x" + Keys.getAddress(publicKey);

                if (addressRecovered.equals(address)) {
                    match = true;
                    break;
                }
            }
        }

        assertEquals(addressRecovered, (address));
        assertTrue(match);
    }
}

https://github.com/web3j/web3j/blob/master/crypto/src/test/java/org/web3j/crypto/ECRecoverTest.java

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