Figure 1 shows these protocols listed under the Advanced tab of the Internet Options dialog in Microsoft Internet Explorer. To establish a secure connection, the browser first asks the Web server for its digital certificate , which provides proof of its identity. When asking the Web server for its digital certificate, the browser also sends along a list of supported encryption algorithms. Once the server sends back the certificate and its choice of encryption algorithm, the browser verifies the certificate by checking the digital signature for signs of tampering, and by confirming that the URL matches the digital certificate's Common Name field. If any of these tests fail, the browser displays a warning message.
Symmetric encryption is used for communication between browser and server.
This means that the same secret session key is used for encrypting and decrypting. The browser generates the key once the server's certificate has been validated, but then needs a secure way to transmit it to the server. This is done through dual-key encryption . The browser encrypts the session key using the server's public key and then transmits this to the server. The server decrypts the session key using its private key and sends an acknowledgement to the browser.