web3js recover returns different address than what signed message

Question

Web3js as of version 1.0.0 beta supports an interface for verifying signed messages: https://github.com/ethereum/web3.js/issues/404

This is documented here: https://web3js.readthedocs.io/en/1.0/web3-eth-accounts.html#recover

Following the documentation, i try to sign and verify a message, and notice the address I get from ecrecover is not the same as the one that created the message.

> let message = "this is a message"
> let account = '0x6eE80F4D7494E61b90c91a7175804018332d6e17'
> let privateKey = '82c290abc9dc56631a62ca9523dcb51b7c2beb6c941bd47ad0332a124eb822ce'
> let signature = '0x21ef296f199e079cae27abffc63389ffd910e91bd7196f389ca2b0177f116d020945a0dbed2ea62d4be17c09947ce33a7a183722e1fc2a75cd9dc9c6bd97d1501b'
> let signatureObject = we3.eth.accounts.sign(message, privateKey)

{ message: 'this is a message',
  messageHash:
   '0x29d8e880f198acda69a1cd82dd2c8e37edc6bb7e84da26527fb8a0cf7d482cda',
  v: '0x1b',
  r:
   '0x21ef296f199e079cae27abffc63389ffd910e91bd7196f389ca2b0177f116d02',
  s:
   '0x0945a0dbed2ea62d4be17c09947ce33a7a183722e1fc2a75cd9dc9c6bd97d150',
  signature:
   '0x21ef296f199e079cae27abffc63389ffd910e91bd7196f389ca2b0177f116d020945a0dbed2ea62d4be17c09947ce33a7a183722e1fc2a75cd9dc9c6bd97d1501b' }

> we3.eth.accounts.recover(signatureObject)

'0x1aB8B2a2BE93b08879b3b3e7eB1EF2D59A544B91'

Notice the address returned is not the same as the address used to sign the message ( the account variable).

I also tried hashing the message before signing using web3.utils.sha3() and web3.eth.accounts.hashMessage(), then passing that hash into sign. They all yield the same address as above.

I have already verified the address and private key I am using are correct.

Answer 1

Prefix your private key with 0x. I'm not sure how it's interpreted without that, but with the 0x prefix you'll get the expected result.