What is SSL and How SSL Works?

What is SSL?

SSL (Secure Sockets Layer) is a standard security technology for establishing an encrypted link between a web server and a browser. This link ensures that all data passed between the web server and browsers remain private and integral¹.

How SSL Works

1. Handshake Process: When a browser connects to a server, the SSL handshake process begins. This involves:

   • The browser requesting the server to identify itself.
   • The server sending a copy of its SSL certificate to the browser.
   • The browser checking the certificate against a list of trusted CAs (Certificate Authorities). If trusted, the browser creates, encrypts, and sends back a session key using the server’s public key.
   • The server decrypting the session key using its private key and establishing a secure encrypted connection.

2. Data Encryption: Once the secure connection is established, all data transmitted between the browser and the server is encrypted using the session key. This ensures that even if the data is intercepted, it cannot be read without the session key.

Example: Implementing SSL in ASP.NET Core MVC with .NET 8

Step 1: Obtain an SSL Certificate

You need to obtain an SSL certificate from a trusted Certificate Authority (CA). This certificate will be used to encrypt the connection between the client and server.

Step 2: Configure Your Server

Depending on your hosting environment (IIS, Kestrel, Azure, etc.), configure your server to use the SSL certificate. For example, in IIS, you can bind the certificate to your website.

Step 3: Configure ASP.NET Core MVC Application

1. Enforce HTTPS: Add the following code in your Program.cs to enforce HTTPS:

var builder = WebApplication.CreateBuilder(args);

// Enforce HTTPS
builder.Services.AddHttpsRedirection(options =>
{
    options.RedirectStatusCode = StatusCodes.Status307TemporaryRedirect;
    options.HttpsPort = 443;
});

var app = builder.Build();

app.UseHttpsRedirection();

app.MapGet("/", () => "Hello World!");

app.Run();

2. Configure Kestrel (if using Kestrel server): Add the following configuration in your appsettings.json:

{
  "Kestrel": {
    "Endpoints": {
      "Https": {
        "Url": "https://localhost:5001",
        "Certificate": {
          "Path": "path/to/your/certificate.pfx",
          "Password": "your-certificate-password"
        }
      }
    }
  }
}

Step 4: Test Your Configuration

After setting up, test your configuration by accessing your application via HTTPS. Ensure that the browser shows a secure connection (usually indicated by a padlock icon).

Summary

SSL ensures secure communication by encrypting data between the client and server. Implementing SSL in an ASP.NET Core MVC application involves obtaining an SSL certificate, configuring your server, and enforcing HTTPS in your application.

For more detailed information, you can refer to the official Microsoft documentation on enforcing HTTPS in ASP.NET Core² and configuring certificate authentication³.