For our new friends:

Every app needs authentication and authorization. Logto is an Auth0 alternative designed for modern apps and SaaS products.

In this article, we will go through the steps to quickly build the Naver sign-in experience (user authentication) with .NET Core (MVC) and  Logto.

Prerequisites

• A running Logto instance. Check out the introduction page to get started.
• Basic knowledge of .NET Core (MVC).
• A usable Naver account.

Create an application in Logto

In you browser, open a new tab and enter the link of Logto Admin Console.

Once the page is loaded, in the "Get Started" section click the View all link to open the application framework list page.

Choose your application type

In the opening modal, scroll to the "Traditional web" section or filter all the available " Traditional web" frameworks using the quick filter checkboxes on the left.

Click the ".NET Core (MVC)" framework card to start creating your application.

Enter application name

Enter the application name, e.g., "Bookstore," and click "Create application."

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate Logto SDK

tip:

• The following demonstration is built on .NET Core 8.0. The SDK is compatible with .NET 6.0 or higher.
• The .NET Core sample projects are available in the GitHub repository.

Installation

Add the NuGet package to your project:

dotnet add package Logto.AspNetCore.Authentication

Add Logto authentication

Open Startup.cs (or Program.cs) and add the following code to register Logto authentication services:

Program.cs

using Logto.AspNetCore.Authentication;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddLogtoAuthentication(options =>
{
  options.Endpoint = builder.Configuration["Logto:Endpoint"]!;
  options.AppId = builder.Configuration["Logto:AppId"]!;
  options.AppSecret = builder.Configuration["Logto:AppSecret"];
});

The AddLogtoAuthentication method will do the following things:

• Set the default authentication scheme to LogtoDefaults.CookieScheme.
• Set the default challenge scheme to LogtoDefaults.AuthenticationScheme.
• Set the default sign-out scheme to LogtoDefaults.AuthenticationScheme.
• Add cookie and OpenID Connect authentication handlers to the authentication scheme.

Sign-in and sign-out flows

Before we proceed, there are two confusing terms in the .NET Core authentication middleware that we need to clarify:

1. CallbackPath: The URI that Logto will redirect the user back to after the user has signed in (the "redirect URI" in Logto)
2. RedirectUri: The URI that will be redirected to after necessary actions have been taken in the Logto authentication middleware.

The sign-in process can be illustrated as follows:

Similarly, .NET Core also has SignedOutCallbackPath and RedirectUri for the sign-out flow.

For the sack of clarity, we'll refer them as follows:

Term we use	.NET Core term
Logto redirect URI	CallbackPath
Logto post sign-out redirect URI	SignedOutCallbackPath
Application redirect URI	RedirectUri

Regarding redirect-based sign-in

1. This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
2. If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.

Configure redirect URIs

note:

In the following code snippets, we assume your app is running on http://localhost:3000/.

First, let's configure the Logto redirect URI. Add the following URI to the "Redirect URIs" list in the Logto application details page:

http://http://localhost:3000//Callback

To configure the Logto post sign-out redirect URI, add the following URI to the "Post sign-out redirect URIs" list in the Logto application details page:

http://http://localhost:3000//SignedOutCallback

Change the default paths

The Logto redirect URI has a default path of /Callback, and the Logto post sign-out redirect URI has a default path of /SignedOutCallback.

You can leave them as are if there's no special requirement. If you want to change it, you can set the CallbackPath and SignedOutCallbackPath property for LogtoOptions:

Program.cs

builder.Services.AddLogtoAuthentication(options =>
{
  // Other configurations...
  options.CallbackPath = "/Foo";
  options.SignedOutCallbackPath = "/Bar";
});

Remember to update the value in the Logto application details page accordingly.

Implement sign-in/sign-out buttons

First, add actions methods to your Controller, for example:

Controllers/HomeController.cs

public class HomeController : Controller
{
  public IActionResult SignIn()
  {
    // This will redirect the user to the Logto sign-in page.
    return Challenge(new AuthenticationProperties { RedirectUri = "/" });
  }

  // Use the `new` keyword to avoid conflict with the `ControllerBase.SignOut` method
  new public IActionResult SignOut()
  {
    // This will clear the authentication cookie and redirect the user to the Logto sign-out page
    // to clear the Logto session as well.
    return SignOut(new AuthenticationProperties { RedirectUri = "/" });
  }
}

Then, add the links to your View:

Views/Home/Index.cshtml

<p>Is authenticated: @User.Identity?.IsAuthenticated</p>
@if (User.Identity?.IsAuthenticated == true) {
  <a asp-controller="Home" asp-action="SignOut">Sign out</a>
} else {
  <a asp-controller="Home" asp-action="SignIn">Sign in</a>
}

It will show the "Sign in" link if the user is not authenticated, and show the "Sign out" link if the user is authenticated.

Test your integration:

Open your .NET Core (MVC) app to test if the integration works. When you click the "Sign In" button, the page should be redirected to a Logto sign-in page, and you should be able to create a new account by entering username and password and complete the sign-in process.

Add Naver connector

To add a social connector, go to the "Connector" tab in the Admin Console, then click on "Social connectors". From there, click "Add social connector".

In the openning modal, select "Naver" and click "Next".

On the next page, you will see a two-column layout with the README content on the left and configuration on the right.

Feel free to follow the README file in place or read the following section to complete the configuration process. If you follow the in-place guide, you can skip the next section.

Set up Naver login

Developer Site Only Korean Support Now

Currently Naver Developers site only supports Korean. Please consider use a translator.

For the Production

• For the production, you have to get review from Naver team. Otherwise, only registered users can sign in.
  • You can add a tester from 맴버관리(Member Manage) menu.
• To get a review, please check 애플리케이션 개발 상태(Application Devlopment Status) from API 설정(API Setting) from your application project setting.

Set up a project in the Naver Developers

• Visit the Naver Developers and sign in with your Naver account.
• Click the Application -> 어플리케이션 등록 from the menu to create new project.
• Follow the instruction below to create application.

Application Name (어플리케이션 이름)

• Type your application name on 어플리케이션 이름 (This name is shown while a user sign in.)

API Usage (사용 API)

• Choose 네이버 로그인(Naver Login) for 사용 API(API Usage)
• Check 이메일 주소(Email Address), 별명(Nickname), 프로필 사진(Profile Image) as 필수(Neccessary) from 권한(Role) (You can check 추가(Add) as optional these options, but you cannot get the information from the user.)

Sign in Open API Service Environment (로그인 오픈 API 서비스 환경)

• For 로그인 오픈 API 서비스 환경(Sign in Open API Service Environment), add two environment PC웹(PC Web) and 모바일웹(Mobile Web).

PC Web (PC 웹)

• For 서비스 URL(Service URL), type http(s)://YOUR_URL (ex. https://logto.io)
• For 네이버 로그인(Naver Login) Callback URL, type http(s)://YOUR_URL/callback/connector_id (e.g. https://logto.io/callback/connector_id)

Mobile Web (Mobile 웹)

• For 서비스 URL(Service URL), type http(s)://YOUR_URL (ex. https://logto.io)
• For 네이버 로그인(Naver Login) Callback URL, type http(s)://YOUR_URL/callback/connector_id (e.g. https://logto.io/callback/connector_id)

⚠️ Caution

The connector_id can be found on the top bar of the Logto Admin Console connector details page.

Configure Logto

Config types

Name	Type
clientId	string
clientSecret	string

clientId

clientId is Client ID of your project. (You can find it from 애플리케이션 정보(Application Info) of your project from Naver developers.)

clientSeceret

clientSecret is Client Secret of your project. (You can find it from 애플리케이션 정보(Application Info) of your project from Naver developers.)

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the Naver connector should be available now.

Enable Naver connector in Sign-in Experience

Switch to the "Sign-in experience" tab, then click the "Sign-up and sign-in" tab.

note:

If it's the first time you enter the tab, you will see a quick introduction about Sign-in Experience and its basic configuration.

Select "None" for the "Sign-up identifier" to provide minimum sign-up effort for Naver sign-in, which may increase your conversion rate.

In the "Social sign-in" section, add "Add Social Connector" and choose "Naver". Then you should be able to see a button with text "Continue with Naver" in the preview section.

Finally, click "Save changes" on the bottom right corner.

Testing and Validation

Return to your .NET Core (MVC) app. You should now be able to sign in with Naver. Enjoy!

Further readings

Protect your API For native and single page apps, you'll need to call one or more API endpoints to retrieve and update data.
Learn more about identifying who's who and keeping your API secure.

User management We know you care about user management and activities, as we also do.
Learn more about how to know your users and see the figures like DAU and MAU graphically.

Localization From one regional business to a global corporate, the willingness to offer the best user experience won't change.
You can change current language phrases or add a new language without friction.

Customer IAM series Our serial blog posts about Customer (or Consumer) Identity and Access Management, from 101 to advanced topics and beyond.