Two-Factor Authentication with Authy

Learn to implement two-factor authentication (2FA) in your web app with Twilio-powered Authy. 2FA helps further secure your users' data by validating more than just a password. This tutorial will show you the code to make it happen.

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About this application

This Express.js sample application demonstrates how to build a login system that uses two factors of authentication to login users. Head to the application's README.md to see how to run the application locally.

Adding two-factor authentication (2FA) to your web application increases the security of your user's data. Multi-factor authentication determines the identity of a user by validating first by logging into the app, and second by validating their mobile device.

For the second factor, we will validate that the user has their mobile phone by either:

  • Sending them a OneTouch push notification to their mobile Authy app
  • Sending them a token through their mobile Authy app
  • Sending them a one-time token in a text message sent with Authy via Twilio. Here's how this works at a high level:

2FA High Level

Let's get started! Click the right arrow above to move to the next step of the tutorial.


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Configuring Authy

If you haven't done so already, now is the time to sign up for Authy. Create your first application, naming it whatever you wish. After you create your application, your "production" API key will be visible on your dashboard:

Authy Dashboard

Once we have an Authy API key, we store it in this initializer file.

Now that we've configured our Express app, let's take a look at how we register a user with Authy.

Registering a User with Authy

When a new User is created we also register the User with Authy.

All Authy needs to get a user set up for your application is its email, phone number and country code. We need to make sure this information is required when the user is signing up.

Once we register the User with Authy we get an id back that we will store as the user's authyId. This is very important since it's how we will verify the identity of our User with Authy.


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Logging in with Authy OneTouch

When a User attempts to login to our website, a second form of identification will be needed. Let's take a look at Authy's OneTouch verification first.

Authy OneTouch Approval

OneTouch works like so:

  • We attempt to send a User a OneTouch Approval Request
  • If the User has OneTouch enabled, we will get a success message back
  • The User hits 'Approve' in their Authy app
  • Authy makes a POST request to our app with an 'Approved' status
  • We log the User in

In the next steps we'll look at how we handle cases where the User does not have OneTouch, or denies the login request.

Sending the OneTouch Request

When our User logs in we immediately attempt to verify their identity with OneTouch. We will fallback gracefully if they don't have a OneTouch device, but we don't know until we try.

Authy lets us pass details with our OneTouch request. These can be messages, logos and any other details we want to send. We could easily send any number of details by appending details['some_detail']. You could imagine a scenario where we send a OneTouch request to approve a money transfer:

details = {
  message: "Request to send money to Jarod's vault",
  from: "Jarod",
  amount: "1,000,000",
  currency: "Galleons"
},

Note: We need some way to check the status of the user's two-factor process, in this case we do so by updating the User.authyStatus attribute. It's important we reset this before we log the user in.


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Configuring the OneTouch callback

In order for our app to know what the User did after we sent the OneTouch request, we need to register a callback endpoint with Authy.

Authy OneTouch Callback

Here in our callback, we look up the user using the authy_id sent with the Authy POST request. Ideally at this point we would probably use a websocket to let our client know that we received a response from Authy. However for this version we're going to keep it simple and just update the authyStatus on the User. Then all our client-side code needs to do is check for user.authyStatus.approved before logging him/her in.

Let's take a look at the client-side code that will be handling this.


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Handling Two-Factor Asyncronously

Our user interface for this example is a single page application written using Backbone and jQuery.

We've already taken a look at what's happening on the server side, so let's step in front of the cameras now and see how our JavaScript is interacting with those server endpoints.

First we hijack the login form submitted and pass the data to our /session controller using Ajax. Depending on how that endpoint responds we will either ask the User for a token or await their OneTouch response.

If we expect a OneTouch response, we will begin polling /authy/status until we either see OneTouch login was either approved or denied. Let's take a look at this controller and see what is happening.


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Falling back to Token

Here is the endpoint that our javascript is polling. It is waiting for the user status to be either 'Approved' or 'Denied'. If the User has approved the OneTouch request, we will save their session as confirmed, which officially logs them in.

If the request was denied we render the /verify page and ask the User to log in with a Token.

Now let's take a look at how we handle two-factor with tokens.

Sending a 2FA Token

2FA Flow Chart Step 5

Once there is an Authy user ID associated with our user model, we can request that an SMS verification token be sent out to the user's phone. Authy supports token validation in their mobile app as well, so if our user has the app it will default to sending a push notification instead of an SMS.

We can call this method on the user instance multiple times if needed. This is what happens every time the user clicks "Resend Code" on the web form we will take a look at next.

Validating the Code

2FA Flow Chart Step 8

Our Express route handler, will grab the code submitted on the form in order to validate it. Connect middleware function executes before this handler and adds a user property to the request object that contains a Mongoose model instance representing the user associated with this session. We use verifyAuthyToken on the User model to check if the code submitted by the user is legit.

Where to next?

That's it! We've just implemented two-factor authentication using three different methods and the latest in Authy technology.

If you're a Node.js developer working with Twilio, you might want to check out these other tutorials.

Account Verification

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Server Notifications via SMS

Faster than e-mail and less likely to get blocked, text messages are great for timed alerts and notifications. Learn how to send out SMS (and MMS) notifications to a list of server administrators.

Did this help?

Thanks for checking this tutorial out! If you have any feedback to share with us, we'd love to hear it. Contact the Twilio Developer Education Team to let us know what you think.