Passwordless authentication using Bitcoin cryptography
npm install bitauthBitAuth
=======
Passwordless authentication using Bitcoin cryptography
BitAuth is a way to do secure, passwordless authentication using the cryptography
in Bitcoin. Instead of using a shared secret, the client signs each request using
a private key and the server checks to make sure the signature is valid and matches
the public key.
Install with Node.js:
``bash`
npm install bitauth
* By signing each request, man in the middle attacks are impossible.
* A nonce is part of the data signed, which prevents replay attacks.
* The cryptography in Bitcoin is rock solid and is securing billions
of dollars worth of bitcoins.
* It uses elliptic curve cryptography which performs much better than RSA.
* Because the private key is never revealed to the server, it does
not need to be exchanged between the server and client over a side channel like
in HMAC.
In each request, the client includes a nonce to prevent replay attacks. The client
signs the full url with the request body concatenated if there is one. The signature
is included in the x-signature header and the public key is included in thex-identity header.
The server verifies that the signature is valid and that it matches the identity (the public key).
It then computes the SIN from the public key, and sees whether that SIN has access
to the requested resource. The nonce is checked to make sure it is higher than
the previously used nonce.
With the growing popularity of Bitcoin, there are already libraries written in
many languages. Because BitAuth uses the same technology as Bitcoin, it is easy
to start using BitAuth.
* Have to keep track of a separate password for every web service. People forget
passwords, encouraging them to reuse passwords and opening themselves up to
having multiple services compromised.
* Brute force attacks on weak passwords.
* Passwords may travel over plaintext
* Passwords in databases being leaked
* Phishing attacks to steal passwords
With BitAuth, users can use the same, strong password to encrypt their keys and
not worry about one service gaining access to another.
In the future, an identity system could be built around BitAuth keys where a user
could create one key to represent an identity which could authenticate against
multiple services.
In order for this to work, there would have to be a browser
integration or plugin which would manage these identities and a Javascript API
where websites could sign requests going to their website with the private key,
but without exposing the private key to the third party sites.
There also needs to be a public place to store SIN's, preferably in
a decentralized blockchain or datastore like namecoin. Key revocations could
be stored here as well as reviews/feedback to build a reputation around an
identity.
Example server
`javascript
var express = require('express');
var bodyParser = require('body-parser');
var rawBody = require('../lib/middleware/rawbody');
var bitauth = require('../lib/middleware/bitauth');
var users = {
'Tf7UNQnxB8SccfoyZScQmb34V2GdEtQkzDz': {name: 'Alice'},
'Tf22EUFxHWh4wmA3sDuw151W5C5g32jgph2': {name: 'Bob'}
};
var pizzas = [];
var app = express();
app.use(rawBody);
app.use(bodyParser());
app.get('/user', bitauth, function(req, res) {
if(!req.sin || !users[req.sin]) return res.send(401, {error: 'Unauthorized'});
res.send(200, users[req.sin]);
});
app.post('/pizzas', bitauth, function(req, res) {
if(!req.sin || !users[req.sin]) return res.send(401, {error: 'Unauthorized'});
var pizza = req.body;
pizza.owner = users[req.sin].name;
pizzas.push(pizza);
res.send(200, req.body);
});
app.get('/pizzas', function(req, res) {
res.send(200, pizzas);
});
app.listen(3000);
`
Example client
`javascript
var request = require('request');
var bitauth = require('../lib/bitauth');
// These can be generated with bitauth.generateSin()
var keys = {
alice: '38f93bdda21a5c4a7bae4eb75bb7811cbc3eb627176805c1009ff2099263c6ad',
bob: '09880c962437080d72f72c8c63a69efd65d086c9e7851a87b76373eb6ce9aab5'
};
// GET
for(k in keys) {
var url = 'http://localhost:3000/user';
var dataToSign = url;
var options = {
url: url,
headers: {
'x-identity': bitauth.getPublicKeyFromPrivateKey(keys[k]),
'x-signature': bitauth.sign(dataToSign, keys[k])
}
};
request.get(options, function(err, response, body) {
if(err) {
console.log(err);
}
if(body) {
console.log(body);
}
});
}
var pizzas = ['pepperoni', 'sausage', 'veggie', 'hawaiian'];
// POST
for(k in keys) {
var url = 'http://localhost:3000/pizzas';
var data = {type: pizzas[Math.floor(Math.random() * pizzas.length)]};
var dataToSign = url + JSON.stringify(data);
var options = {
url: url,
headers: {
'x-identity': bitauth.getPublicKeyFromPrivateKey(keys[k]),
'x-signature': bitauth.sign(dataToSign, keys[k])
},
json: data
};
request.post(options, function(err, response, body) {
if(err) {
console.log(err);
}
if(body) {
console.log(body);
}
});
}
`
javascript
var bitauth = require('bitauth');
app.use( bitauth.middleware );
``