Data privacy and compliance (GDPR) in HLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is GDPR and why is it important in system design?

GDPR stands for General Data Protection Regulation. It is a law that protects personal data of people in the EU. In system design, it ensures that user data is handled safely and with respect to privacy.

intermediate

Name three key principles of GDPR that affect system architecture.

1. Data Minimization: Only collect data needed.
2. Purpose Limitation: Use data only for stated reasons.
3. Data Subject Rights: Allow users to access, correct, or delete their data.

beginner

What is 'data subject consent' and how should systems handle it?

Data subject consent means users agree clearly to how their data is used. Systems must get explicit permission before collecting data and allow users to withdraw consent anytime.

intermediate

Explain the concept of 'data breach notification' under GDPR.

If personal data is leaked or accessed wrongly, GDPR requires notifying authorities within 72 hours and informing affected users quickly to reduce harm.

advanced

How can system design support the 'right to be forgotten'?

Systems should allow users to request deletion of their personal data. This means designing data storage and backups so data can be fully removed without breaking the system.

Which of the following is NOT a GDPR principle?

A Data Minimization

B Unlimited Data Retention

C Purpose Limitation

D Data Subject Rights

GDPR requires limiting how long data is kept, so unlimited retention is not allowed.

Under GDPR, how soon must a data breach be reported to authorities?

A Within 72 hours

B Within 24 hours

C Within 1 week

D No specific time

GDPR mandates reporting data breaches within 72 hours of discovery.

What does 'data subject consent' require?

A No consent needed for personal data

B Implicit agreement by using the service

C Explicit and informed permission before data collection

D Consent only for marketing emails

GDPR requires clear, explicit consent before collecting personal data.

Which system design feature helps support the 'right to be forgotten'?

A Data encryption

B Data anonymization

C Data replication

D Data deletion mechanisms

Systems must allow complete deletion of user data to comply with this right.

What is the main goal of GDPR in system design?

A Protect user privacy and data rights

B Maximize data collection

C Increase system speed

D Reduce server costs

GDPR focuses on protecting personal data and respecting user privacy.

Describe how GDPR principles influence the design of a user data storage system.

Think about what data you keep, how you get permission, and how users can control their data.

Explain the steps a system should take when a data breach occurs under GDPR.

Consider detection, communication, and prevention.

Practice

1. What is the main purpose of GDPR in system design?

easy

A. To reduce server costs by deleting all user data immediately

B. To protect user privacy and ensure data is handled responsibly

C. To allow unlimited data collection for marketing

D. To increase system performance by caching user data

Solution

1. Step 1: Understand GDPR's goal

   GDPR aims to protect personal data and privacy of users in the EU.

2. Step 2: Match purpose to options

   Only To protect user privacy and ensure data is handled responsibly mentions protecting privacy and responsible data handling, which aligns with GDPR.

3. Final Answer:

   To protect user privacy and ensure data is handled responsibly -> Option B

4. Quick Check:

   GDPR = Protect privacy [OK]

Hint: GDPR = user privacy protection [OK]

Common Mistakes:

• Confusing GDPR with performance or cost goals
• Thinking GDPR allows unlimited data collection
• Ignoring privacy as the core focus

2. Which of the following is a correct way to obtain user consent under GDPR?

easy

A. Collecting data first, then asking for consent later

B. Pre-checked boxes that users can uncheck anytime

C. Assuming consent if the user visits the website

D. Clear opt-in with explicit user action before data collection

Solution

1. Step 1: Review GDPR consent rules

   Consent must be freely given, specific, informed, and unambiguous with clear user action.

2. Step 2: Evaluate options

   Only Clear opt-in with explicit user action before data collection describes explicit opt-in before data collection, which is GDPR compliant.

3. Final Answer:

   Clear opt-in with explicit user action before data collection -> Option D

4. Quick Check:

   Consent = explicit opt-in [OK]

Hint: Consent requires clear opt-in, not assumptions [OK]

Common Mistakes:

• Using pre-checked boxes as valid consent
• Assuming visiting equals consent
• Collecting data before consent

3. Consider a system that stores user data with a 'right to be forgotten' feature. Which action correctly implements this under GDPR?

def delete_user_data(user_id):
    # Step 1: Mark user data as deleted
    database.mark_deleted(user_id)
    # Step 2: Remove data from active systems
    cache.remove(user_id)
    # Step 3: Permanently erase data after retention period
    schedule_permanent_delete(user_id, days=30)

medium

A. This implementation violates GDPR because data is not deleted immediately

B. This implementation is incorrect because it does not notify the user

C. This implementation respects GDPR by delaying permanent deletion for 30 days

D. This implementation is incorrect because it does not encrypt user data

Solution

1. Step 1: Understand GDPR's 'right to be forgotten'

   GDPR allows data to be deleted but permits a retention period for legal or operational reasons.

2. Step 2: Analyze code steps

   Data is marked deleted, removed from active use, and scheduled for permanent erase after 30 days, which is acceptable.

3. Final Answer:

   This implementation respects GDPR by delaying permanent deletion for 30 days -> Option C

4. Quick Check:

   Right to be forgotten allows retention delay [OK]

Hint: Deletion can be delayed for legal retention [OK]

Common Mistakes:

• Expecting immediate permanent deletion always
• Confusing notification with deletion requirements
• Thinking encryption replaces deletion

4. A system logs user IP addresses without anonymization. Which GDPR compliance issue does this cause?

log_user_access(user_id, ip_address):
    logs.save({'user': user_id, 'ip': ip_address, 'time': now()})

medium

A. It violates data minimization by storing unnecessary personal data

B. It violates consent because IP addresses are not encrypted

C. It violates breach notification rules by logging IPs

D. It violates data portability by not exporting IP addresses

Solution

1. Step 1: Identify GDPR principles involved

   Data minimization requires only collecting data necessary for the purpose.

2. Step 2: Analyze IP logging

   Storing full IP addresses without anonymization may be unnecessary and excessive, violating minimization.

3. Final Answer:

   It violates data minimization by storing unnecessary personal data -> Option A

4. Quick Check:

   Data minimization = minimal necessary data [OK]

Hint: Store only data you really need [OK]

Common Mistakes:

• Confusing encryption with consent
• Mixing breach notification with logging
• Thinking data portability applies here

5. You are designing a system to comply with GDPR. Which combination of features best supports compliance?

• 1. Data encryption at rest and in transit
• 2. User consent management with audit logs
• 3. Automatic data deletion after user request
• 4. Collecting all user data for analytics without opt-out

hard

A. Features 1, 2, and 3 only

B. Features 2 and 4 only

C. Features 1 and 4 only

D. All features 1, 2, 3, and 4

Solution

1. Step 1: Evaluate each feature for GDPR compliance

   Feature 1 (encryption) protects data; Feature 2 manages consent properly; Feature 3 respects user deletion rights; Feature 4 violates consent and data minimization.

2. Step 2: Select compliant combination

   Only features 1, 2, and 3 together support GDPR compliance fully.

3. Final Answer:

   Features 1, 2, and 3 only -> Option A

4. Quick Check:

   Consent + encryption + deletion = GDPR compliance [OK]

Hint: Exclude features violating consent or data minimization [OK]

Common Mistakes:

• Including data collection without opt-out
• Ignoring encryption importance
• Overlooking user deletion rights