.NET Core C# Two-factor Authentication Quickstart
As of November 2022, Twilio no longer provides support for Authy SMS/Voice-only customers. Customers who were also using Authy TOTP or Push prior to March 1, 2023 are still supported. The Authy API is now closed to new customers and will be fully deprecated in the future.
For new development, we encourage you to use the Verify v2 API.
Existing customers will not be impacted at this time until Authy API has reached End of Life. For more information about migration, see Migrating from Authy to Verify for SMS.
Adding two-factor authentication to your application is the easiest way to increase security and trust in your product without unnecessarily burdening your users. This quickstart guides you through building an ASP.NET Core, AngularJS, and SQL Server application that restricts access to a URL. Four Authy API channels are demoed: SMS, Voice, Soft Tokens and Push Notifications.
Ready to protect your toy app's users from nefarious balaclava wearing hackers? Dive in!
Sign Into - or Sign Up For - a Twilio Account
Create a new Twilio account (you can sign up for a free Twilio trial), or sign into an existing Twilio account.
Create a New Authy Application
Once logged in, visit the Authy Console. Click on the red 'Create New Aplication' (or big red plus ('+') if you already created one) to create a new Authy application then name it something memorable.
You'll automatically be transported to the Settings page next. Click the eyeball icon to reveal your Production API Key.
Copy your Production API Key to a safe place, you will use it during application setup.
Setup Authy on Your Device
This two-factor authentication demos two channels which require an installed Authy app to test: Soft tokens and push authentications. While SMS and voice channels will work without the client, to try out all four authentication channels download and install the Authy app for Desktop or Mobile:
Clone and Setup the Application
Start by cloning our repository. Then, enter the directory and install dependencies:
git clone https://github.com/TwilioDevEd/account-security-csharp.git cd account-security-csharp/src/AccountSecurity dotnet restore
Next, open the file
appsettings.json. There, edit the
AuthyApiKey, pasting in the API Key from the above step (in the console), and save.
Install and Launch SQL Server
When a user registers with your application, a request is made to Twilio to add that user to your App, and a
user_id is returned. In this demo, we'll store the returned
user_id in an MSSQL database.
On Windows, you can install the free SQL Server Express:
On Linux or Mac, run it as a docker container:
docker run -e 'ACCEPT_EULA=Y' -e 'SA_PASSWORD=yourStrong(!)Password' \ -p 1433:1433 --name mssql -d microsoft/mssql-server-linux:latest
Make sure your
DefaultConnection connection string in
appsettings.json is correct for your SQL Server installation. You may need to change the
localhost\\SQLEXPRESS if running MSSQL Server Express on Windows. Or, you may need to change the password if you selected a different one when starting your Docker container.
Run the database migrations:
dotnet ef database update -v
Once you have added your API Key, you are ready to run! Run the app with:
dotnet run --environment development
Try the .NET Core C# Two-Factor Demo
With your phone (optionally with the Authy client installed) nearby, open a new browser tab and navigate to
Enter your information and invent a password, then hit 'Register'. Your information is passed to Twilio (you will be able to see your user immediately in the console), and the application is returned a
Now visit https://localhost:5001/login/ and login. You'll be presented with a happy screen:
If your phone has the Authy app installed, you can immediately enter a soft token from the client to Verify. Additionally, you can try a push authentication simply by pushing the labeled button.
If you do not have the Authy app installed, the SMS and voice channels will also work in providing a token. To try different channels, you can logout to start the process again.
And there you go, two-factor authentication is on and your .NET Core C# App is protected!
Now that you are keeping the hackers out of this demo app using two-factor authentication, you can find all of the detailed descriptions for options and API calls in our Authy API Reference. If you're also building a registration flow, also check out our Twilio Verify product and the Verification Quickstart which uses this codebase.
For additional guides and tutorials on account security and other products, in C# and in other languages, take a look at the Docs.
Need some help?
We all do sometimes; code is hard. Get help now from our support team, or lean on the wisdom of the crowd by visiting Twilio's Stack Overflow Collective or browsing the Twilio tag on Stack Overflow.