Cyber Security
Internet and Its Uses
SSL (Secure Socket Layer) is a security protocol that encrypts data sent between a web browser and a web server, so that intercepted data cannot be read.
When a browser connects to a secure site, the browser and server carry out an SSL handshake: the browser asks the server to identify itself, the server sends back its digital certificate, and the browser checks that the certificate is authentic. The two then agree on the keys used to encrypt the session. After the handshake, all data passing between them is encrypted, so even if it is intercepted it is meaningless to the attacker. A site protected by SSL shows https and a padlock symbol in the address bar. SSL is what makes activities such as online banking and shopping safe to carry out over the public internet.
Common exam question
Stating how SSL secures data in transmission
Question: State how the SSL protocol secures data for transmission, or complete a paragraph about how an SSL connection starts, choosing terms from a list (1–5 marks).
Asked in 2 of the 17 papers. The one-mark version accepts either idea: SSL encrypts the data, or it uses digital certificates.
The paragraph version gives one mark per gap, in order, and follows how the connection begins: the web browser asks the web server to identify itself, the web server replies with its digital certificate, the web browser checks that the certificate is authentic, and only then does encrypted transmission begin. The list also offers distractors such as unencrypted, HTTP, URL and file server, and the five answers use only three terms. Keep track of which side is acting: the browser asks and checks, while the server proves who it is.