Implementing a minimal OpenID Server

In this article, we'll explore how to quickly set up an OpenID server using the SimpleIdServer.IdServer NuGet package in an ASP.NET Core application. This solution is perfect for developers who need a lightweight identity server implementation.

Quick Start with a Pre-Configured Template

If you prefer an even faster setup, you can generate a fully pre-configured solution by simply running the following command:

cmd.exe

dotnet new idserverempty

This command creates a new ASP.NET Core project that is already configured as a minimal OpenID server. It saves you the steps of manually installing the NuGet package and setting up the configuration.

Getting Started Manually

For those who wish to understand the details or customize the implementation, follow these steps:

Step 1: Create the Project and Install the Package

First, create a new ASP.NET Core project and install the required NuGet package:

cmd.exe

dotnet add package SimpleIdServer.IdServer

Step 2: Configure the OpenID Server

Open your Program.cs file and add the following code to configure the OpenID server:

Program.cs

var scope = ScopeBuilder.CreateApiScope("api1", false).Build();
var clients = new List<Client>
{
    ClientBuilder.BuildApiClient("client", "secret").AddScope(scope).Build()
};
var scopes = new List<Scope>
{ 
    scope
};
webApplicationBuilder.AddSidIdentityServer()
    .AddDeveloperSigningCredential()
    .AddInMemoryClients(clients)
    .AddInMemoryScopes(scopes);

var app = webApplicationBuilder.Build();
app.UseSid();
app.Run();

Code Explanation

1. API Scope Creation: An API scope named api1 is created.
2. Client Configuration: A client is set up with the ID client and secret secret, and the API scope is added to its configuration.
3. Server Setup: The identity server is configured to use in-memory clients and scopes.
4. Development Signing Credential: A developer signing credential is added for testing purposes.

Usage

With this configuration, you can now obtain access tokens using the client credentials flow. The client is configured with the api1 scope, allowing it to request access tokens for that specific API scope using the client_credentials grant type.