What is TLS?
TLS (Transport Layer Security) is a cryptographic protocol designed to secure communication over a network. It encrypts data sent between clients (like a web browser) and servers, preventing eavesdropping and tampering. TLS replaces its predecessor, SSL (Secure Sockets Layer), and the latest version is TLS 1.3.
✔ TLS ensures
- Encryption: Protects data from being intercepted.
- Authentication: Verifies the identity of the communicating parties.
- Integrity: Ensures data is not modified in transit.
Common Uses of TLS
-
Securing websites (HTTPS)
- Encrypting emails (SMTP, IMAP, POP3 with STARTTLS)
- Protecting VoIP and instant messaging
- VPN connections
What is HTTPS?
HTTPS (Hypertext Transfer Protocol Secure) is simply HTTP (Hypertext Transfer Protocol) + TLS. It ensures that data exchanged between a web browser and a web server is encrypted using TLS.
✔ HTTPS ensures
- Secure browsing by encrypting data
- Authentication via SSL/TLS certificates (issued by a Certificate Authority, CA)
- Protection against MITM (Man-in-the-Middle) attacks
How does HTTPS work?
- A browser requests an HTTPS connection to a website.
- The server responds with an SSL/TLS certificate.
- The browser verifies the certificate with a CA (Certificate Authority).
- A TLS handshake occurs, setting up encryption keys.
- Secure communication begins.
📌 Without HTTPS, attackers can intercept sensitive data like passwords and credit card numbers.
How to Enforce HTTPS in .NET?
If you're developing a .NET Core / .NET 5+ application, you should enforce HTTPS in your web API or MVC app.
A. Enforcing HTTPS in ASP.NET Core
Modify the Program.cs to redirect HTTP to HTTPS:
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
app.UseHttpsRedirection(); // Redirects HTTP to HTTPS
app.UseAuthorization();
app.MapControllers();
app.Run();
B. Enforcing TLS 1.2+ in .NET
If you want to enforce TLS 1.2 or TLS 1.3 in a .NET application:
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls13;
For HttpClient in .NET Core
var handler = new HttpClientHandler
{
SslProtocols = SslProtocols.Tls12 | SslProtocols.Tls13
};
var client = new HttpClient(handler);
Checking TLS Support on a Website
To check if a website supports TLS 1.2 or TLS 1.3, you can use:
- Online tools: SSL Labs SSL Test
- Browser Console: Press F12 → Security Tab (for Chrome/Edge)
Why is HTTPS & TLS Important?
- ✅ Prevents data breaches (protects passwords, credit cards, API keys)
- ✅ Improves SEO ranking (Google prefers HTTPS)
- ✅ Required for modern browsers (Chrome & Firefox block HTTP)
- ✅ Enables HTTP/2 & HTTP/3 (which require TLS)
Conclusion
TLS is a security protocol that encrypts data in transit. HTTPS is HTTP + TLS, securing websites against cyber threats. .NET apps should enforce TLS 1.2+ and redirect HTTP to HTTPS for security.