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