.NET Core C# Two-factor Authentication Quickstart

(warning)

Warning

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!

Create a New Authy Application

Once logged in, visit the Authy Console. Click on the red 'Create New Application' (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:

Download Authy App

Clone and Setup the Application

Start by cloning our repository. Then, enter the directory and install dependencies:

1git clone https://github.com/TwilioDevEd/account-security-csharp.git
2cd account-security-csharp/src/AccountSecurity
3dotnet 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 .

Add Your Application API Key

Enter the API Key from the Account Security console.

1{
2  "Logging": {
3    "LogLevel": {
4      "Default": "Warning"
5    }
6  },
7  "AllowedHosts": "*",
8  "ConnectionStrings": {
9    "DefaultConnection": "Server=127.0.0.1;Database=account_security;Trusted_Connection=True;MultipleActiveResultSets=true;Integrated Security=False;User ID=sa;Password=yourStrong(!)Password"
10  },
11  "AuthyApiKey": "Your-Authy-Api-Key"
12}

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:

Install SQL Server Express for Windows

On Linux or Mac, run it as a docker container:

1docker run -e 'ACCEPT_EULA=Y' -e 'SA_PASSWORD=yourStrong(!)Password' \
2
3-p 1433:1433 --name mssql -d microsoft/mssql-server-linux:latest

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Warning

Make sure your DefaultConnection connection string in appsettings.json is correct for your SQL Server installation. You may need to change the Server to 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 https://localhost:5001/register/

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 user_id.

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 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.

Two Factor Authentication Channels

1using System;
2using System.Collections.Generic;
3using System.Net;
4using System.Net.Http;
5using System.Threading.Tasks;
6using AccountSecurity.Models;
7using Microsoft.Extensions.Configuration;
8using Microsoft.Extensions.Logging;
9using Newtonsoft.Json;
10using Newtonsoft.Json.Linq;
11
12
13namespace AccountSecurity.Services
14{
15  public interface IAuthy
16  {
17    Task<string> registerUserAsync(RegisterViewModel user);
18    Task<TokenVerificationResult> verifyTokenAsync(string authyId, string token);
19    Task<TokenVerificationResult> verifyPhoneTokenAsync(string phoneNumber, string countryCode, string token);
20    Task<string> sendSmsAsync(string authyId);
21    Task<string> phoneVerificationCallRequestAsync(string countryCode, string phoneNumber);
22    Task<string> phoneVerificationRequestAsync(string countryCode, string phoneNumber);
23    Task<string> createApprovalRequestAsync(string authyId);
24    Task<object> checkRequestStatusAsync(string onetouch_uuid);
25  }
26
27  public class Authy : IAuthy
28  {
29    private readonly IConfiguration Configuration;
30    private readonly IHttpClientFactory ClientFactory;
31    private readonly ILogger<Authy> logger;
32    private readonly HttpClient client;
33
34    public string message { get; private set; }
35
36    public Authy(IConfiguration config, IHttpClientFactory clientFactory, ILoggerFactory loggerFactory)
37    {
38      Configuration = config;
39      logger = loggerFactory.CreateLogger<Authy>();
40
41      ClientFactory = clientFactory;
42      client = ClientFactory.CreateClient();
43      client.BaseAddress = new Uri("https://api.authy.com");
44      client.DefaultRequestHeaders.Add("Accept", "application/json");
45      client.DefaultRequestHeaders.Add("user-agent", "Twilio Account Security C# Sample");
46
47      // Get Authy API Key from Configuration
48      client.DefaultRequestHeaders.Add("X-Authy-API-Key", Configuration["AuthyApiKey"]);
49    }
50
51    public async Task<string> registerUserAsync(RegisterViewModel user)
52    {
53      var userRegData = new Dictionary<string, string>() {
54                { "email", user.Email },
55                { "country_code", user.CountryCode },
56                { "cellphone", user.PhoneNumber }
57            };
58      var userRegRequestData = new Dictionary<string, object>() { };
59      userRegRequestData.Add("user", userRegData);
60      var encodedContent = new FormUrlEncodedContent(userRegData);
61
62      var result = await client.PostAsJsonAsync("/protected/json/users/new", userRegRequestData);
63
64      logger.LogDebug(result.Content.ReadAsStringAsync().Result);
65
66      result.EnsureSuccessStatusCode();
67
68      var response = await result.Content.ReadAsAsync<Dictionary<string, object>>();
69
70      return JObject.FromObject(response["user"])["id"].ToString();
71    }
72
73    public async Task<TokenVerificationResult> verifyTokenAsync(string authyId, string token)
74    {
75      var result = await client.GetAsync($"/protected/json/verify/{token}/{authyId}");
76
77      logger.LogDebug(result.ToString());
78      logger.LogDebug(result.Content.ReadAsStringAsync().Result);
79
80      var message = await result.Content.ReadAsStringAsync();
81
82      if (result.StatusCode == HttpStatusCode.OK)
83      {
84        return new TokenVerificationResult(message);
85      }
86
87      return new TokenVerificationResult(message, false);
88    }
89
90    public async Task<TokenVerificationResult> verifyPhoneTokenAsync(string phoneNumber, string countryCode, string token)
91    {
92      var result = await client.GetAsync(
93          $"/protected/json/phones/verification/check?phone_number={phoneNumber}&country_code={countryCode}&verification_code={token}"
94      );
95
96      logger.LogDebug(result.ToString());
97      logger.LogDebug(result.Content.ReadAsStringAsync().Result);
98
99      var message = await result.Content.ReadAsStringAsync();
100
101      if (result.StatusCode == HttpStatusCode.OK)
102      {
103        return new TokenVerificationResult(message);
104      }
105
106      return new TokenVerificationResult(message, false);
107    }
108
109    public async Task<string> sendSmsAsync(string authyId)
110    {
111      var result = await client.GetAsync($"/protected/json/sms/{authyId}?force=true");
112
113      logger.LogDebug(result.ToString());
114
115      result.EnsureSuccessStatusCode();
116
117      return await result.Content.ReadAsStringAsync();
118    }
119
120    public async Task<string> phoneVerificationCallRequestAsync(string countryCode, string phoneNumber)
121    {
122      var result = await client.PostAsync(
123          $"/protected/json/phones/verification/start?via=call&country_code={countryCode}&phone_number={phoneNumber}",
124          null
125      );
126
127      var content = await result.Content.ReadAsStringAsync();
128
129      logger.LogDebug(result.ToString());
130      logger.LogDebug(content);
131
132      result.EnsureSuccessStatusCode();
133
134      return await result.Content.ReadAsStringAsync();
135    }
136
137    public async Task<string> phoneVerificationRequestAsync(string countryCode, string phoneNumber)
138    {
139      var result = await client.PostAsync(
140          $"/protected/json/phones/verification/start?via=sms&country_code={countryCode}&phone_number={phoneNumber}",
141          null
142      );
143
144      var content = await result.Content.ReadAsStringAsync();
145
146      logger.LogDebug(result.ToString());
147      logger.LogDebug(content);
148
149      result.EnsureSuccessStatusCode();
150
151      return await result.Content.ReadAsStringAsync();
152    }
153
154    public async Task<string> createApprovalRequestAsync(string authyId)
155    {
156      var requestData = new Dictionary<string, string>() {
157                { "message", "OneTouch Approval Request" },
158                { "details", "My Message Details" },
159                { "seconds_to_expire", "300" }
160            };
161
162      var result = await client.PostAsJsonAsync(
163          $"/onetouch/json/users/{authyId}/approval_requests",
164          requestData
165      );
166
167      logger.LogDebug(result.ToString());
168      var str_content = await result.Content.ReadAsStringAsync();
169      logger.LogDebug(str_content);
170
171      result.EnsureSuccessStatusCode();
172
173      var content = await result.Content.ReadAsAsync<Dictionary<string, object>>();
174      var approval_request_data = (JObject)content["approval_request"];
175
176      return (string)approval_request_data["uuid"];
177    }
178
179    public async Task<object> checkRequestStatusAsync(string onetouch_uuid)
180    {
181      var result = await client.GetAsync($"/onetouch/json/approval_requests/{onetouch_uuid}");
182      logger.LogDebug(result.ToString());
183      var str_content = await result.Content.ReadAsStringAsync();
184      logger.LogDebug(str_content);
185
186      result.EnsureSuccessStatusCode();
187
188      return await result.Content.ReadAsAsync<object>();
189    }
190  }
191
192  public class TokenVerificationResult
193  {
194    public TokenVerificationResult(string message, bool succeeded = true)
195    {
196      this.Message = message;
197      this.Succeeded = succeeded;
198    }
199
200    public bool Succeeded { get; set; }
201    public string Message { get; set; }
202  }
203}

And there you go, two-factor authentication is on and your .NET Core C# App is protected!

What's Next?

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.

.NET Core C# Two-factor Authentication Quickstart

Warning

Sign Into - or Sign Up For - a Twilio Account

Create a New Authy Application

Setup Authy on Your Device

Clone and Setup the Application

Add Your Application API Key

Install and Launch SQL Server

Warning

Try the .NET Core C# Two-Factor Demo

Two Factor Authentication Channels

What's Next?