Design a global data masking and tokenization platform
PremiumSecurity systemHard
- Security architecture
- Low latency
- Distributed caching
Quick answer
This security system interview question asks you to design a global data masking and tokenization platform. Aim for a design that protects users and data without blocking legitimate use, then explain the threats, controls, detection and trade-offs. Interviewers want to see how you model threats and layer defences.
The problem
Design a Global Data Masking and Tokenization Platform for a large enterprise. To comply with strict data privacy regulations, internal microservices are prohibited from storing plaintext Personally Identifiable Information (PII) such as SSNs, emails, and phone numbers in their respective databases.
Services must call your platform to tokenize PII before writing to disk, and call it again to detokenize the data when reading. The system must deterministically generate tokens, enforce Identity and Access Management (IAM) policies to ensure only authorized services can detokenize specific fields, and emit a tamper-proof audit log of every operation.
What must a global data masking and tokenization platform do?
- Deterministic Tokenization: Convert plaintext PII to a token. The transformation must be deterministic (the same plaintext string must always yield the exact same token) to allow downstream microservices and data warehouses to perform SQL JOINs using the tokenized values.
- Policy-Driven Detokenization: Revert a token back to plaintext only if the calling service's policy permits access to that specific data classification.
What scale should you design for?
Use these numbers in your estimates.
The scale numbers unlock with this questionUnlock
Key concepts
- Security architecture
- Low latency
- Distributed caching
- Stream processing
- Data governance
- Compliance
How you’ll practise
- Requirements and assets
- Threat model
- Identity and access
- Data protection
- Detection and response
- Wrap-up
Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.
What do interviewers look for?
In any security system design round.
- Starts with a clear threat model
- Layers defences instead of relying on one control
- Covers authentication, authorisation and secrets
- Plans detection, alerting and response
- Protects data in transit and at rest
- Balances security against usability and cost
Questions people ask about this interview question
- Which design type is this question?
- It is a security system question. You design a global data masking and tokenization platform and explain your choices the way you would in an interview.
- Is this question asked at entry level?
- It is marked Hard. It suits engineers preparing for senior interviews, where you are expected to drive the discussion and go deep on trade-offs.
- What should I cover first?
- Start with what must be protected, from whom and what a breach would cost. Agree on scope with the interviewer before you design anything.
- Can I practise it for free?
- It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.
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Updated · Written by the SevyDevy team