Understanding How HTTPS Works

The TLS handshake is the first step in establishing a secure connection between the client (browser) and the server. This process involves several key steps:

Client Hello:

• TLS Version: The client sends a message to the server indicating the highest TLS version it supports.

• Supported Cipher Suites: It includes a list of supported cipher suites (encryption algorithms).

• Random Data: This ensures the uniqueness of the session.

plaintext

Client: Hello

Server Hello:

• Cipher Suite Selection: The server responds with the chosen cipher suite from the list provided by the client.

• TLS Version: The server confirms the TLS version to be used.

• Random Data: Similar to the client, the server sends its random data.

plaintext

Server: Hello

Server Certificate:

• Digital Certificate: The server sends its digital certificate, which includes the server’s public key and is signed by a trusted Certificate Authority (CA).

• Verification: The client verifies the server’s certificate against a list of trusted CAs.

plaintext

Server: [Digital Certificate]

Key Exchange:

• Key Exchange Message: Based on the chosen cipher suite, the client and server exchange keys. This step may involve different methods such as RSA or Diffie-Hellman.

• Session Key: A shared session key is generated, which will be used to encrypt the data transmitted between the client and server.

plaintext

Client & Server: [Key Exchange]