About Security and data integrity in A Level Computer Science
Security and data integrity is one of the 10 main topics in our A Level Computer Science (Cambridge (CAIE) 9618) question bank, and about 4% of its real questions come from it. Tayyari Karo has 50 real questions on this topic from 2021 to 2026, from Paper 1, Paper 2, Paper 3. By difficulty: 26 medium, 22 easy, 2 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
Try 8 real questions
These are real past-paper questions. Think of your answer first, then open the explanation.
May/June 2026 · Paper 1 · Security and data integrity
When data is entered into the database it is validated and verified. (i) Explain how validation and verification support data integrity within a database. [4]
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1 mark each to max 4: validation ensures that data meets certain criteria; validation prevents the input of inappropriate data; verification makes sure the data entered matches the original/intended data; verification prevents data being accidentally changed from the original; any example of validation/verification in practice, e.g. entering a password twice.
Validation checks that data is reasonable; verification checks it was entered as intended.
May/June 2025 · Paper 1 · Security and data integrity
(a) Identify and describe one method of restricting the risks posed by an unauthorised person intercepting data whilst it is being transferred across the internet.
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Method: Encryption
Description:
• Data is encoded/scrambled using a key to create cipher text
• If intercepted it cannot be understood without being decrypted using a key
3 marks: 1 for method, 1 each for description points.
October/November 2025 · Paper 1 · Security and data integrity
Explain what is meant by a virus and pharming.
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Virus: Malicious program that replicates itself and deletes/alters files.
Pharming: Malicious code installed to redirect user to fake website to obtain personal data.
Two definitions with explanations.
October/November 2025 · Paper 3 · Security and data integrity
Explain the purpose of a digital certificate.
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1. Provides public key
2. Validates private key used to create digital signature
3. Makes digital signature virtually impossible to spoof
Three marks for explanation.
October/November 2024 · Paper 1 · Security and data integrity
(b) Give two benefits of distributing software using a proprietary software licence.
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• The owner/developer can earn a fee
• Comprehensive support is usually offered so problems can be easily solved
• The software is usually well tested so few bugs
2 marks: 1 for each bullet point to max 2.
May/June 2022 · Paper 1 · Security and data integrity
A teacher is writing examination papers on a laptop computer. The computer is connected to the internet. The teacher is concerned about the security and privacy of the papers.
(a) State the difference between the security of data and the privacy of data.
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Security prevents against loss (of data) while privacy prevents unauthorised access (to data).
1 mark.
May/June 2021 · Paper 1 · Security and data integrity
(b) INPUT x
IF x = "" THEN
OUTPUT "Invalid"
ENDIF
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Presence (check)
1 mark.
October/November 2021 · Paper 1 · Security and data integrity
(c) Compare viruses and spyware. Give two similarities and one difference.
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Similarities:
• Both are pieces of malicious software
• Both are downloaded/installed/run without the user's knowledge
• Both can pretend to be / are embedded in other legitimate software
• Both run in the background
Difference:
• Virus can damage computer data; spyware only records/accesses data
• Virus does not send data out; spyware sends recorded data to third party
• Virus replicates itself; spyware does not replicate itself
3 marks: 1 per similarity to max 2, 1 for difference.
