browser-authenticator.js/README.md

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# Browser Authenticator
Two- / Multi- Factor Authenication (2FA / MFA) for browser JavaScript
![](https://blog.authy.com/assets/posts/authenticator.png)
There are a number of apps that various websites use to give you 6-digit codes to increase security when you log in:
* Authy (shown above) [iPhone](https://itunes.apple.com/us/app/authy/id494168017?mt=8) | [Android](https://play.google.com/store/apps/details?id=com.authy.authy&hl=en) | [Chrome](https://chrome.google.com/webstore/detail/authy/gaedmjdfmmahhbjefcbgaolhhanlaolb?hl=en) | [Linux](https://www.authy.com/personal/) | [OS X](https://www.authy.com/personal/) | [BlackBerry](https://appworld.blackberry.com/webstore/content/38831914/?countrycode=US&lang=en)
* Google Authenticator [iPhone](https://itunes.apple.com/us/app/google-authenticator/id388497605?mt=8) | [Android](https://play.google.com/store/apps/details?id=com.google.android.apps.authenticator2&hl=en)
* Microsoft Authenticator [Windows Phone](https://www.microsoft.com/en-us/store/apps/authenticator/9wzdncrfj3rj) | [Android](https://play.google.com/store/apps/details?id=com.microsoft.msa.authenticator)
* GAuth [FxOS](https://marketplace.firefox.com/app/gauth/)
There are many [Services that Support MFA](http://lifehacker.com/5938565/heres-everywhere-you-should-enable-two-factor-authentication-right-now),
including Google, Microsoft, Facebook, and Digital Ocean for starters.
This module uses [`botp`](https://github.com/Daplie/botp) which implements `TOTP` [(RFC 6238)](https://www.ietf.org/rfc/rfc6238.txt)
(the *Authenticator* standard), which is based on `HOTP` [(RFC 4226)](https://www.ietf.org/rfc/rfc4226.txt)
to provide codes that are exactly compatible with all other *Authenticator* apps and services that use them.
Demo
====
<https://daplie.github.io/browser-authenticator/>
Usage
=====
```bash
bower install authenticator --save
```
```javascript
'use strict';
var authenticator = window.Authenticator;
authenticator.generateKey().then(function (formattedKey) {
// "acqo ua72 d3yf a4e5 uorx ztkh j2xl 3wiz"
authenticator.generateToken(formattedKey).then(function (formattedToken) {
// "957 124"
authenticator.verifyToken(formattedKey, formattedToken).then(function (result) {
// { delta: 0 }
});
authenticator.verifyToken(formattedKey, '000 000').then(function (result) {
// null
});
});
});
```
### Browsers that support WebCrypto
In total there are only a few hundred lines of uncompressed code here.
Each file is very small.
```
<script src="bower_components/unibabel/index.js"></script>
<script src="bower_components/unibabel/unibabel.hex.js"></script>
<script src="bower_components/unibabel/unibabel.base32.js"></script>
<script src="bower_components/botp/sha1-hmac.js"></script>
<script src="bower_components/botp/index.js"></script>
<script src="bower_components/authenticator/authenticator.js"></script>
```
### Browsers that do not support WebCrypto
```
<!-- forge.hmac -->
<script src="bower_components/forge/js/util.js"></script>
<script src="bower_components/forge/js/sha1.js"></script>
<script src="bower_components/forge/js/hmac.js"></script>
<!-- forge.random.getBytes -->
<script src="bower_components/forge/js/sha256.js"></script>
<script src="bower_components/forge/js/cipher.js"></script>
<script src="bower_components/forge/js/cipherModes.js"></script>
<script src="bower_components/forge/js/aes.js"></script>
<script src="bower_components/forge/js/prng.js"></script>
<script src="bower_components/forge/js/random.js"></script>
```
TODO: I'd love some help pruning the important bits out of the forge code.
Just using an alternate CPRNG would be very helpful in trimming the fat.
## API
### generateKey()
generates a 32-character (160-bit) base32 key
### generateToken(formattedKey)
generates a 6-digit (20-bit) decimal time-based token
### verifyToken(formattedKey, formattedToken)
validates a time-based token within a +/- 30 second (90 seconds) window
returns `null` on failure or an object such as `{ delta: 0 }` on success
QR Code
-------
See <https://davidshimjs.github.io/qrcodejs/> and <https://github.com/soldair/node-qrcode>.
![](http://cdn9.howtogeek.com/wp-content/uploads/2014/10/sshot-7-22.png)
Example use with `qrcode.js` in the browser:
```javascript
'use strict';
var el = document.querySelector('.js-qrcode-canvas');
var link = "otpauth://totp/{{NAME}}?secret={{KEY}}";
var name = "Your Service";
// remove spaces, hyphens, equals, whatever
var key = "acqo ua72 d3yf a4e5 uorx ztkh j2xl 3wiz".replace(/\W/g, '').toLowerCase();
var qr = new QRCode(el, {
text: link.replace(/{{NAME}}/g, name).replace(/{{KEY}}/g, key)
});
```
Formatting
----------
All non-alphanumeric characters are ignored, so you could just as well use hyphens
or periods or whatever suites your use case.
These are just as valid:
* "acqo ua72 d3yf a4e5 - uorx ztkh j2xl 3wiz"
* "98.24.63"
0, 1, 8, and 9 also not used (so that base32).
To further avoid confusion with O, o, L, l, I, B, and g
you may wish to display lowercase instead of uppercase.
TODO: should this library replace 0 with o, 1 with l (or I?), 8 with b, 9 with g, and so on?
90-second Window
----------------
The window is set to +/- 1, meaning each token is valid for a total of 90 seconds
(-30 seconds, +0 seconds, and +30 seconds)
to account for time drift (which should be very rare for mobile devices)
and humans who are handicapped or otherwise struggle with quick fine motor skills (like my grandma).