Security, privacy and data integrity

Paper 1 · Unit 6. Protecting data and systems, threats, validation and verification.

1. Security, privacy and integrity

Term	Meaning
Data security	Protecting data from loss, damage or unauthorised access
Data privacy	Keeping personal data confidential and used only for agreed purposes (protected by data protection laws)
Data integrity	Making sure data is accurate, complete and consistent

Security is needed for both data and computer systems, because threats can corrupt, steal or destroy data and stop systems working.

2. Security measures

Measure	How it protects
User accounts and passwords	Only authorised users can log in; access rights limit what each user can do
Biometrics	Fingerprints, face or iris recognition are unique and hard to copy
Firewall	Monitors incoming and outgoing traffic and blocks traffic that breaks the rules
Anti-virus / anti-spyware	Detects and removes malware
Encryption	Scrambles data so it is meaningless without the key
Digital signatures and certificates	Confirm the sender and that data has not been altered
Back-ups	A copy can be restored if data is lost or corrupted
Disk mirroring (RAID)	Data is written to two disks at once, so one can fail without data loss

3. Threats

Threat	Description
Malware: virus	Attaches to files and replicates when they run; can delete or corrupt data
Malware: worm	Replicates itself across a network without user action
Malware: spyware	Secretly records activity, e.g. keystrokes, and sends it to a third party
Hacking	Gaining unauthorised access to a system
Phishing	Fake emails or messages trick users into giving personal details
Pharming	Malicious code redirects users to a fake website even if they type the correct URL

Preventing threats: firewalls, anti-malware, strong passwords, keeping software updated, user training, checking URLs and certificates, and not opening suspicious attachments.

4. Validation and verification

Validation checks that data is sensible and follows rules; it cannot prove the data is correct. Verification checks that data has been entered or transferred accurately.

Validation check	Example
Range check	Age between 0 and 120
Format check	A date in the form DD/MM/YYYY
Length check	A password at least 8 characters long
Presence check	A required field is not empty
Existence check	The product code exists in the database
Limit check	Only one boundary, e.g. quantity ≥ 1
Check digit	An extra digit calculated from the others, e.g. ISBN, detects input errors

Verification method	How
Double entry	Data is entered twice and the two versions are compared
Visual check	The user compares the entered data with the original
Parity check	An extra bit makes the number of 1s even (or odd); a mismatch shows an error
Checksum	A value calculated from a block of data is sent with it and recalculated on arrival
Parity block	Parity bits for each byte and each column identify the exact bit in error

5. Examiner tips

1. Validation vs verification: validation checks reasonableness, verification checks accuracy of copying.
2. A parity check cannot detect an even number of bit errors.
3. Phishing needs the user to act; pharming redirects without them noticing.
4. Firewall: say it filters traffic using rules, not just “blocks hackers”.
5. Name the check and give an example relevant to the scenario.

6. Practice questions

7. Topic test: predict your grade