DAuth

DAuth is a simple decentralized authentication system tied to identities on the Ethereum Blockchain.

Server side integration (Verifier URL)

Your server should expose one endpoint on to which the users will send login requests. The endpoint must

Parse username, code and hashcode from the query parameters
Get user's DAuth Handler and Public Key from dauth.co or any other server of your choice
Generate a short random token string
Send a POST request to the DAuth Handler with the following parameters : code, codehash, username, cipher. The POST request will respond with the decipherd value using the user's private key.
Redirect user appropriately, handle successful and failed logins

Node.js NPM package

npm install dauth-verifier

const dauth = require('node-dauth-verifier');
router.get("/", function(req, res, next){
    dauth.verify(req.query.username, req.query.code, req.query.hashcode).then(function(data){
        console.log("Login successful");
        // ... Logic for successful login ...
    }).catch(function(error){
        console.log("Login Failed");
        // ... Logid for failed login here ...
    });
});

For more details on the npm package visit the node-dauth-verifier repository

Node.js self implemented

var BASE_URL = "https://dauth.co/";
var axios = require('axios');
var crypto = require('crypto');
var cryptico = require('cryptico');

router.get("/", function(req, res, next){
    var username = req.query.username;
    var code = req.query.code;
    var hashcode = req.query.hashcode;
    var urlGetter = BASE_URL + "utils/url?username="+username;
    var addressGetter = BASE_URL + "utils/address?username="+username;
    var keyGetter = BASE_URL + "utils/key?username="+username;
    axios.get(urlGetter).then(function(aUrl){
	axios.get(keyGetter).then(function(aKey){
	    var tokenRaw = crypto.createHash('sha256').update(Math.random().toString()).digest('base64').substr(0,10);
	    var encrypted = cryptico.encrypt(tokenRaw, aKey.data, "").cipher;
	    axios.post(aUrl.data+"?action=verify", {username:username,code:code, hashcode:hashcode, cipher: encrypted}).then(function(decrypted){
		if(decrypted.data == tokenRaw){
		    axios.get(addressGetter).then(function(address){
  		        //redirect to success page
		    }).catch(function(error){
		        //redirect to login failed page
		    });
		    return;
		}
		//redirect to login failed page
	    });
	}).catch(function(error){
		//redirect to login failed page
	});
    }).catch(function(error){
		//redirect to login failed page
    });

});

Client side integration

Generate the widget using this link

Architecture

Components

DAuth Server : Anybody can clone this repository and setup a DAuth server, one such server has been set up at http://dauth.co. The DAuth Server consists of a DAuth Login Page and a DAuth Handler.
DAuth Handler : The DAuth Handler takes handles the user's private keys on his/her behalf.
DAuth Login Page : The DAuth Login Page is where the user must enter the password. Once the username and password has been entered, a session code is generated and passed on to the verifier endpoint.
Verifier Endpoint : The verifier endpoint takes the sends a challenge request to the DAuth Handler. The DAuth Handler will be able to pass the challenge only if it holds the user's private keys.

Flow of control

A user can register on a DAuth server. This server may be either self hosted (recommended) or hosted by a trusted third party.
Upon registration, the user must sign a transaction to reserve a username and broadcast the public key on the Ethereum blockchain. The user also broadcasts the DAuth Server location onchain.
Any service wanting to authenticate a user against the claimed address, may create a challenge. A challenge is a random string encrypted with the user's public key available on the Ethereum blockchain. This challenge is sent to the DAuth Handler. The user shall be considered successfully logged in if the DAuth handler passes the challenge. A challenge is passed if the Handler is able to recover the random string which was encrypted as a part of the challenge, by using the user's private key.

Gotchas

The private and public key are different from the ones used for the Ethereum Transactions. The Ethers are thus always safe in this process.
Dauth Handler address is defined as DAuth_Server_Location?action=verify
Dauth Login Page address is defined as DAuth_Server_Location?action=login

Bonus : APIs

getAddress

https://dauth.co/utils/address?username=[PUT USERNAME HERE] : gives the Ethereum address that has been associated with the given username

getPublicKey

http://dauth.co/utils/key?username=[PUT USERNAME HERE] : gives the Public Key that has been associated with the given username

getDauthUrl

http://dauth.co/utils/url?username=[PUT USERNAME HERE] : gives the address of the DAuth Server. DAuth Handler and DAuth Login page urls may be constructed using this address as mentioned above.

peterdouglas/dauth