Understanding SSL/TLS - How It Works End-to-End

Hello everyone, welcome back to the CK 2024 blog series! This is the 20th entry in our series. Before diving into our next topic on certificates in Kubernetes, I wanted to ensure we have a solid understanding of how SSL/TLS works. If you're already familiar with this topic, feel free to skip to the next blog in the series if not, let's get started!

What is SSL/TLS?

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are protocols that provide a secure communication channel between a client (user) and a server over the internet. They are essential for protecting data transmitted over the web, ensuring that sensitive information such as usernames, passwords, and credit card details are encrypted and secure from eavesdropping and tampering.

The Basics: HTTP vs. HTTPS

When a user sends a request to a server (for example, accessing a website), this communication can happen over HTTP (HyperText Transfer Protocol) or HTTPS (HTTP Secure). HTTP is not secure, meaning data sent over it can be intercepted and read by anyone who has access to the data flow. HTTPS, on the other hand, encrypts the data using SSL/TLS, making it secure.

Understanding SSL/TLS with an Example

Let's break down how SSL/TLS works with a simple example. Imagine a user trying to access a web server. Here are the steps involved:

1. Client Requests Access: The user sends an HTTP request to the server.
2. Server Requests Authentication: The server asks for the user's authentication details (username and password).
3. Client Sends Credentials: The user sends their credentials to the server.
4. Server Authenticates and Responds: The server authenticates the user and sends back the requested data.

However, this process over HTTP is vulnerable to attacks. A hacker can intercept the data (credentials) and misuse it. This is where SSL/TLS comes into play.

Introducing Encryption

To secure this communication, we use encryption. There are two main types of encryption:

1. Symmetric Encryption: The same key is used for both encryption and decryption. While simple, it has a significant vulnerability: if a hacker intercepts the key, they can decrypt all data.

2. Asymmetric Encryption: This uses a pair of keys - a public key for encryption and a private key for decryption. This method enhances security as the private key is never shared.

How SSL/TLS Uses Asymmetric Encryption

Here’s how SSL/TLS uses asymmetric encryption to secure communication:

• Server Generates Keys: The server generates a public and private key pair using tools like OpenSSL.
• Client Requests Access: The user sends an HTTP request to the server.
• Server Sends Public Key: The server responds with its public key.
• Client Encrypts Data: The client encrypts their data (e.g., a symmetric key for further communication) using the server’s public key.
• Data Sent to Server: The encrypted data is sent to the server.
• Server Decrypts Data: The server uses its private key to decrypt the data.

Certificates and Certificate Authorities (CA)

To further enhance security, SSL/TLS uses certificates issued by Certificate Authorities (CA). These certificates validate that the public key truly belongs to the server and not an imposter. Here's how it works:

1. Server Creates a CSR: The server generates a Certificate Signing Request (CSR).
2. CA Validates CSR: The CA validates the CSR, ensuring the server's identity.
3. CA Issues Certificate: The CA issues a certificate containing the server’s public key and other identity details.
4. Client Validates Certificate: When the client receives the server’s certificate, it validates the certificate against the CA’s public certificates stored in the client’s browser.

The Importance of SSL/TLS

Using SSL/TLS ensures that:

1. Data integrity is maintained.
2. Communication is secure and encrypted.
3. Users can trust that they are communicating with the intended server.

Conclusion

Understanding SSL/TLS is crucial for ensuring secure communication over the internet. In our next post, we'll dive deeper into how certificates are used specifically in Kubernetes, how to create a certificate signing request, and more.

Stay tuned, and if you have any questions or need further clarification, feel free to reach out. See you in the next post!

For further reference, check out the detailed YouTube video here:

Happy Learning!!