Ethereum Ðapp Development - Video 19 | Implementing an Authentication Scheme

index.html

<h1>Example Text</h1>

<script>
  var message = "DecypherTV";
  var userEthereumClient;
  
  window.addEventListener("load", function() {
    userEthereumClient = window.web3;
  })
  
  document.querySelector("h1").addEventListener("click", function(event) {
    userEthereumClient.eth.sign(userEthereumClient.eth.coinbase, window.web3.sha3(message), function(error, data) {
      var signedAuthMessage = data;
      document.cookie = "signedAuthMessage=" + signedAuthMessage;
    })
  })
  
  // Require EthUtil NPM Module
  var sigDecoded = EthUtil.fromRPCSig(signedAuthMessage);
  var recoveredPub = EthUtil.ecrecover(window.web3.sha3(message), sigDecoded.v, sigDecoded.r, sigDecoded.s);
  var recoveredAddress = EthUtil.pubToAddress(recoveredPub).toString("hex");
  
  // Authentication Logic (user is logged in?)
  userEthereumClient.eth.coinbase === recoveredAddress;
  
</script>