SSL (Secure Sockets Layer)

Secure Sockets Layer (SSL) is a standard security technology for establishing an encrypted link between a server and a client — typically a web server (website) and a browser, or a mail server and a mail client.

SSL enables the secure transmission of sensitive information such as credit card numbers, social security numbers, and login credentials. Data sent between browsers and web servers is typically sent in plain text.

An attacker can see and use information if they are able to intercept all data sent between a browser and a web server.

All browsers can communicate with secured web servers via the SSL protocol. However, in order to establish a secure connection, both the browser and the server require what is known as an SSL Certificate.

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A process known as a "SSL Handshake" is used by the browser and the web server to create an SSL connection when a browser tries to access a website that is protected by SSL.

To establish an SSL connection, three keys are used: the ????????????, ??????????????, and ?????????????? keys. Anything encrypted with the public key can only be decrypted with the private key, and the reverse is true.

Browser connects to a web server (website) secured with SSL (https). Browser requests that the server identify itself.

Server sends a copy of its SSL Certificate, including the server’s public key.

The browser compares the certificate root to a list of trusted CAs and ensures that the certificate is not expired or revoked, and that its common name is valid for the website to which it is connecting. If the browser believes the certificate, it generates, encrypts, and returns a symmetric session key using the public key of the server.

Server decrypts the symmetric session key using its private key and sends back an acknowledgement encrypted with the session key to start the encrypted session.

Server and Browser now encrypt all transmitted data with the session key.

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