Explain the HTTPS Handshake.

HTTPS overlays HTTP on top of the SSL/TLS protocol to encrypt communication:

1. Client Hello: Client sends supported TLS versions, cipher suites, and a random string.
2. Server Hello: Server responds with the selected TLS version, selected cipher suite, another random string, and its SSL Certificate.
3. Authentication: Client validates the SSL certificate signature against its list of trusted Certificate Authorities (CAs).
4. Key Exchange:
   • Client generates a Pre-Master Secret, encrypts it using the server's public key from the certificate, and sends it to the server.
   • Server decrypts the Pre-Master Secret using its private key.
5. Generate Session Keys: Both client and server use the Pre-Master Secret and the initial random strings to calculate a symmetric Session Key.
6. Handshake Finished: Both sides send encrypted verification messages confirming that all future messages will be encrypted using the symmetric Session Key.