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Encryption

OCR GCSE Computer Science (J277) · Computer systems (Paper 1) › Networks, connections and protocols › Wired and wireless networks, protocols and layers

Practise Encryption. 12 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.

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Sample questions

Written for this site in the style of OCR exam questions. They are not taken from real past papers.

Question 1Easy3 marks
(a) State what is meant by encryption.[1]
(b) What is needed to decrypt data that has been encrypted?
Tick (✓) one box.[1]
  • A firewall
  • A MAC address
  • The key
  • A switch
(c) Give one example of data that should be encrypted when it is sent over the Internet.[1]
Show the answer and mark scheme
(a)
  • scrambling / encoding data using an algorithm and a key, so it cannot be understood without the key
(b) Answer: The key
(c)
  • passwords / bank or card details / personal information / medical records
Question 2Medium4 marks
(a) Explain how encryption protects data sent over a wireless network.[3]
(b) Encryption does not stop data from being intercepted. State what it does do.[1]
Show the answer and mark scheme
(a)
  • the data is encrypted using an algorithm and a key before it is sent
  • if the data is intercepted, it cannot be understood / is meaningless without the key
  • only the intended receiver, who has the key, can decrypt it
(b)
  • it stops intercepted data from being understood / used
Question 3Hard6 marks
(a) Explain why encryption is important for a laptop that could be lost or stolen.[2]
(b) Explain why encryption is important when a user enters card details on a shopping website.[2]
(c) A user is tricked into entering their password on a fake website that uses HTTPS. Explain why encryption did not protect the password.[2]
Show the answer and mark scheme
(a)
  • if the storage is encrypted, the data cannot be read without the key / password
  • so a thief cannot access the files, even by removing the drive
(b)
  • the card details travel across many networks and could be intercepted
  • HTTPS encrypts them, so intercepted data is meaningless
(c)
  • the password was only encrypted between the user and the fake website
  • the attacker runs the fake site, so they receive / can decrypt the password; encryption only stops other people reading the data in transit

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