Explain what happens during the establishment of a secure HTTPS connection in terms of the handshake process.

During the establishment of a secure connection via HTTPS, a process called TLS handshake occurs. Its goal is to establish a secure communication channel between the client and the server.

Main steps of the TLS handshake:

1. Client greets the server — sends a list of supported TLS protocol versions, a set of cipher suites, and a random number.
2. Server responds — selects encryption parameters from those offered by the client, sends its certificate (with the public key), and its random number.
3. Certificate verification — the client verifies the authenticity of the server's certificate through the trust chain (CA).
4. Key exchange — the client generates a secret (pre-master secret), encrypts it with the server's public key, and sends it.
5. Session key generation — both parties use the secret and random numbers to generate symmetric encryption keys and integrity verification keys.
6. Handshake completion — the client and server exchange Finished messages, confirming the successful establishment of a secure channel.

After this, all data exchange occurs using symmetric encryption, ensuring confidentiality and data integrity.

Thus, the TLS handshake provides:

• Server authentication (and optionally client authentication).
• Negotiation of encryption parameters.
• Secure key exchange for symmetric encryption.