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Signing operations

In this guide, we'll cover how to sign data and transactions using web3.js. Whether it's signing data with an account, signing transactions, or using wallets and private keys, we'll walk you through the basic steps. Let's get started!

Sign Data With an Account​

In this example we are creating a random account web3.eth.account.create(), but you can also import a specific account by using web3.eth.accounts.privateKeyToAccount('0x...')

import { create } from 'web3-eth-accounts';

// the create method returns a `Web3Account` object
// the account contains an `address` and `privateKey` and allows you to be able to encrypt, signData and signTransaction.
const account = create(); //this is the same as web3.eth.accounts.create();

/* ↳
{
address: '0xbD504f977021b5E5DdccD8741A368b147B3B38bB',
privateKey: 'privateKey',
signTransaction: [Function: signTransaction],
sign: [Function: sign],
encrypt: [AsyncFunction: encrypt]
}
*/

account.sign('hello world');
/* ↳ 
{
  message: 'hello world',
  messageHash: '0xd9eba16ed0ecae432b71fe008c98cc872bb4cc214d3220a36f365326cf807d68',
  v: '0x1b',
  r: '0xe4fce466ef18f6cd8b4f4175a9a04cd2872a1a6a8cfc2ff67fb0cfd6d78ec758',
  s: '0x37ca3a789976f1854d16e50a04caf2e06ee14b0ac4a5878b43929767f2008288',
  signature: '0xe4fce466ef18f6cd8b4f4175a9a04cd2872a1a6a8cfc2ff67fb0cfd6d78ec75837ca3a789976f1854d16e50a04caf2e06ee14b0ac4a5878b43929767f20082881b'
}
*/

Sign a Transaction With an Account​

In this example we are importing a specific account by using web3.eth.accounts.privateKeyToAccount('0x...') but you can also create a random account by using web3.eth.account.create().

import { Web3 } from 'web3';

const web3 = new Web3(/* PROVIDER */);

const privateKey = '0x4651f9c219fc6401fe0b3f82129467c717012287ccb61950d2a8ede0687857ba'
const account = web3.eth.accounts.privateKeyToAccount(privateKey);

// Magic happens inside signTransaction. If a transaction is sent from an account that exists in a wallet, it will be automatically signed using that account.
signedTransaction = await account.signTransaction({
  from: account.address,
  to: '0xe4beef667408b99053dc147ed19592ada0d77f59',
  value: '0x1',
  gas: '300000',
  gasPrice: await web3.eth.getGasPrice(),
});

console.log(signedTransaction);
/* ↳
{
messageHash: '0xfad22c3ab5ecbb6eec934a21243ee1866fbbd3786f4e8e8ec631b917ef65174d',
v: '0xf4f6',
r: '0xc0035636d9417f63fdd418bc545190e59b58a4ff921bbf4efebf352dac211f11',
s: '0x4944d746ff12c7bca41f77c8f7d75301cea8b205e021dfde34d09d5bdccc713d',
rawTransaction:
    '0xf866808477359400830493e094e4beef667408b99053dc147ed19592ada0d77f59018082f4f6a0c0035636d9417f63fdd418bc545190e59b58a4ff921bbf4efebf352dac211f11a04944d746ff12c7bca41f77c8f7d75301cea8b205e021dfde34d09d5bdccc713d',
transactionHash: '0xa3fed275c97abc4a160cd9bef3ec90206686f32821a8fd4e01a04130bff35c1a',
};
*/

Signing data/messages using a wallet​

Signing with a wallet
import { Web3 } from 'web3';

const web3 = new Web3(/* PROVIDER */);

// create a `Wallet` with 1 account inside
const wallet = web3.eth.accounts.wallet.create(1);

const message = web3.utils.utf8ToHex('Hello world'); // sign only takes hexstrings, so turn message to hexstring

const signedMessage = web3.eth.sign(message, wallet[0].address);

console.log(signedMessage);
/* ↳
{
  message: '0x48656c6c6f20776f726c64',
  messageHash: '0x8144a6fa26be252b86456491fbcd43c1de7e022241845ffea1c3df066f7cfede',
  v: '0x1c',
  r: '0x3a420906f331896cb5db1366cdaeef1f0b14f9f71d72c178e87b76f8b31f3f36',
  s: '0x32ffccc78638c1d7e46dbf16041ddaef90ab50a85eeeaa46f8c496a39237831a',
  signature: '0x3a420906f331896cb5db1366cdaeef1f0b14f9f71d72c178e87b76f8b31f3f3632ffccc78638c1d7e46dbf16041ddaef90ab50a85eeeaa46f8c496a39237831a1c'
}
*/

Signing data/messages using a privateKey​

import { Web3 } from 'web3';

const web3 = new Web3(/* PROVIDER */);

const privateKey = '0x4651f9c219fc6401fe0b3f82129467c717012287ccb61950d2a8ede0687857ba';

const message = 'Hello world';
const signedMessage = web3.eth.accounts.sign(message, privateKey);

console.log(signedMessage);
/* ↳
{
  message: 'Hello world',
  messageHash: '0x8144a6fa26be252b86456491fbcd43c1de7e022241845ffea1c3df066f7cfede',
  v: '0x1c',
  r: '0xb669ef385082d7c4393522ab2fc37f8684fe948b313fb64b7cb8bee851b765f1',
  s: '0x26eec81e9900d25500c13024b273e238cfb2a4d4554b79f74b372e1132b6cb2f',
  signature: '0xb669ef385082d7c4393522ab2fc37f8684fe948b313fb64b7cb8bee851b765f126eec81e9900d25500c13024b273e238cfb2a4d4554b79f74b372e1132b6cb2f1c'
}
*/