This PCSE practice question tests your understanding of ensuring data protection. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A security engineer needs to encrypt data at rest in Cloud Storage using a key that is not managed by Google Cloud. The key must be stored on-premises and provided with each API call for data access. Which encryption approach should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use customer-supplied encryption keys (CSEK) by providing the key in the request headers.
Customer-supplied encryption keys (CSEK) allow you to provide your own AES-256 key with each API call to Cloud Storage. The key is not stored by Google Cloud; it is used only in memory to encrypt/decrypt data and then discarded, meeting the requirement of on-premises key storage and per-API-call key provision.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use customer-managed encryption keys (CMEK) with key material imported from an on-premises HSM.
Why it's wrong here
CMEK keys are stored in Cloud KMS, not on-premises.
✗
Use Cloud KMS with a key stored in an on-premises HSM via Cloud External Key Manager.
Why it's wrong here
Cloud EKM still requires Google Cloud to manage the key through the external key manager; the key is not provided per API call.
✗
Use Google-managed encryption keys with an organizational policy to disable automatic encryption.
Why it's wrong here
Google-managed keys are managed by Google, not the customer.
✓
Use customer-supplied encryption keys (CSEK) by providing the key in the request headers.
Why this is correct
CSEK allows you to provide your own key with each API call, keeping the key on-premises.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the distinction between CMEK (key material managed in Cloud KMS) and CSEK (key provided per request), and the trap here is that candidates confuse 'customer-managed' with 'customer-supplied,' assuming CMEK satisfies the 'provided with each API call' requirement when it does not.
Detailed technical explanation
How to think about this question
CSEK uses a customer-provided AES-256 key that is passed in the x-goog-encryption-key header of each Cloud Storage API request. Google Cloud uses this key to encrypt or decrypt the object data in memory, then discards the key; it never stores the key on disk. This approach is ideal for regulatory environments requiring that the cloud provider never have persistent access to the raw encryption key, but it imposes the operational burden of key management and rotation on the customer.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Ensuring data protection — This question tests Ensuring data protection — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use customer-supplied encryption keys (CSEK) by providing the key in the request headers. — Customer-supplied encryption keys (CSEK) allow you to provide your own AES-256 key with each API call to Cloud Storage. The key is not stored by Google Cloud; it is used only in memory to encrypt/decrypt data and then discarded, meeting the requirement of on-premises key storage and per-API-call key provision.
What should I do if I get this PCSE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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