TLS Certificates

This article was written using chatGPT.

Transport Layer Security (TLS) certificates play a crucial role in securing communication over the internet. The certificates establish encrypted connections between a client and a web server, ensuring that data exchanged between them remains confidential and tamper-proof. Here's a simplified explanation of how TLS certificates work:

1. Initiating the Connection:

- When you visit a website by typing its URL or clicking on a link, your web browser (the client) sends a request to the web server hosting that website (the server).

- The web server responds, initiating a handshake process to establish a secure connection.

2. Requesting the Certificate:

- During the initial handshake, the server sends its TLS certificate to the client. This certificate typically includes the server's public key (the certificate) and some information about the server, such as its domain name.

- The browser (client) receives the certificate and begins the process of verifying its authenticity.

3. Certificate Verification:

- The browser (client) checks whether the certificate is valid and trustworthy. This involves several steps:

- Confirming that the certificate is signed by a trusted Certificate Authority (CA). CAs are organizations that vouch for the legitimacy of websites. All devices come pre-loaded with third-party CAs provided by domain registries (e.g., GoDaddy, VeriSign) or certificate provider e.g., Digicert.

- Checking if the certificate has expired. Certificates are issued with an expiration date.

- Verifying that the certificate matches the domain name of the website you're trying to visit.

4. Public Key Exchange:

- If the browser (client) successfully verifies the certificate, it extracts the server's public key from the certificate.

- The browser then generates a random symmetric encryption key, known as a session key, to be used for encrypting and decrypting data during this specific session.

5. Secure Communication:

- The browser (client) encrypts the session key with the server's public key and sends it back to the server. The server retrieves the session key by decrypting use its private key.

- Both the browser and the server now have the session key and can use it to encrypt and decrypt data for the remainder of the session.

- This symmetric encryption is faster than asymmetric encryption (used for public and private keys), making data transfer more efficient.

6. Encrypted Data Transfer:

- With the secure connection established, data exchanged between the browser (client) and the server is encrypted using the session key.

- This encryption ensures that even if intercepted by malicious actors, the data remains unintelligible without the session key.

7. Session Closure:

- When the session ends (e.g., when you close the browser or navigate away from the website), the session key is discarded.

- This means that even if someone were to obtain the session key, it would be useless for future sessions.

In summary, TLS certificates provide a mechanism for websites or servers to prove their authenticity and enable secure, encrypted communication between them and the browsers (clients). This encryption helps protect sensitive information, such as login credentials and personal data, from eavesdropping and tampering during transmission over the internet.

This article discusses the high level of how to generate a server identity certificate.