Data security: integrity

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. A hacker changes a student's bank balance from $50 to $5000 without permission. Which security principle is broken?

A Availability

B Integrity

2. Which statement best describes data integrity?

A Data can be read by anyone who asks for it

B Data stays accurate and is only changed by authorised people

3. A bank teller with the right permissions corrects a mistyped balance and the change is logged. Is integrity still intact?

A Yes, because an authorised person made the change

B No, because the balance was changed

4. Which situation is a breach of integrity?

A A user edits their own account balance without permission

B The bank website is offline for maintenance

5. Which control helps protect the integrity of a bank balance?

A Giving only authorised staff write permission

B Giving every customer write permission to all accounts

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Integrity		AGRANT UPDATE ON accounts TO bank_manager;
2UPDATE accounts SET balance = 999999 WHERE accountId = 7;		BThe change was made by an unauthorised person and was accepted without any check, so the balance is no longer accurate and integrity is broken.
3Only authorised users may change a balance, which protects integrity		CA tampered balance: an unauthorised change that breaks data integrity
4A balance must stay accurate, so a rule blocks impossible changes		DALTER TABLE accounts ADD CHECK (balance >= 0);
5GRANT UPDATE ON accounts TO PUBLIC;		EData stays accurate and unaltered unless an authorised person changes it
6A customer edits their own balance from 500 to 5000, and the bank accepts it as correct.		FEvery user can change balances, so anyone could tamper with them and integrity is not protected. Only authorised users should get UPDATE.

Definitions

Integrity

Fill in the Blanks

Complete each line of code by filling in the missing parts.

______ accounts SET balance = 9999 WHERE id = 4;

if storedBalance _ expectedBalance then print "Tampering detected" end if

if ____ = "admin" then balance ← newBalance end if

GRANT ______ ON accounts TO customer;

balance DECIMAL(10,2) _____ (balance >= 0)

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A balance ← 500

B input userRole

C input amount

D if userRole ≠ "teller" then

E balance ← balance - amount

F end if

Question 2

A oldTotal ← sum(transactions)

B if oldTotal = balance then

C print "Balance tampered"

D else

E print "Balance tampered"

Question 3

A define checkBalance(stored, now

B if stored ≠ now then

C return "Tampered"

D end if

E return "Intact"

Question 4

A input amount

B newBalance ← balance amount

C write userId, newBalance to log

Question 5

A if role = "teller" then

B balance = balance + deposit

C else

D print "Access denied"

E end if

Answer Key

Data security: integrity

Section A: Quick Questions

B — Integrity

B — Data stays accurate and is only changed by authorised people

A — Yes, because an authorised person made the change

A — A user edits their own account balance without permission

A — Giving only authorised staff write permission

Section B: Match the Pairs

Integrity → Data stays accurate and unaltered unless an authorised person changes it

UPDATE accounts SET balance = 999999 WHERE accountId = 7; → A tampered balance: an unauthorised change that breaks data integrity

Only authorised users may change a balance, which protects integrity → GRANT UPDATE ON accounts TO bank_manager;

A balance must stay accurate, so a rule blocks impossible changes → ALTER TABLE accounts ADD CHECK (balance >= 0);

GRANT UPDATE ON accounts TO PUBLIC; → Every user can change balances, so anyone could tamper with them and integrity is not protected. Only authorised users should get UPDATE.

A customer edits their own balance from 500 to 5000, and the bank accepts it as correct. → The change was made by an unauthorised person and was accepted without any check, so the balance is no longer accurate and integrity is broken.

Section C: Definitions

Integrity — Data stays accurate and unaltered unless an authorised person changes it, so a tampered bank balance breaks integrity.

Section D: Fill in the Blanks

UPDATE accounts SET balance = 9999
WHERE id = 4;

if storedBalance ≠ expectedBalance then
  print "Tampering detected"
end if

if role = "admin" then
  balance ← newBalance
end if

GRANT SELECT ON accounts TO customer;

balance DECIMAL(10,2) CHECK (balance >= 0)

Section E: Spot the Error

D — The condition is reversed, so everyone except a teller could change the balance. Only an authorised user may alter it: if userRole = "teller" then.

C — When the stored balance matches the transaction total, the data is intact. This branch should print "Integrity OK", not report tampering.

A — The closing bracket of the parameter list is missing. It should be define checkBalance(stored, now).

B — The arithmetic operator is missing, so the new balance cannot be calculated. It should be newBalance ← balance - amount.

B — = compares two values and does not store anything. Assignment needs the arrow: balance ← balance + deposit.