PCSE Ensuring Data Protection Practice Question
A company uses Customer-Supplied Encryption Keys (CSEK) for Compute Engine persistent disks. They want to ensure that Google does not store the key material. What must they do?
⚠ Common exam trap
Many exam-takers confuse CSEK with CMEK (Customer-Managed Encryption Keys) and assume Cloud KMS or Cloud HSM can be used to satisfy the 'no storage' requirement, but those services inherently store key material within Google's control.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use the gcloud compute disks create command with the --csek-key-file flag to supply the key, and do not store the key in Cloud KMS.
Customer-Supplied Encryption Keys (CSEK) allow you to provide your own raw AES-256 key material when creating a persistent disk. By using the `gcloud compute disks create` command with the `--csek-key-file` flag, you supply the key directly to the API, and Google uses it only in memory to encrypt the disk; it does not persist the key material on Google's infrastructure. The key file is stored locally by the customer, ensuring Google never retains the key.
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 the gcloud compute disks create command with the --csek-key-file flag to supply the key, and do not store the key in Cloud KMS.
Why this is correct
CSEK keys are supplied per API call and not stored by Google.
- ✗
Enable Cloud HSM to protect the key.
Why it's wrong here
CSEK keys are not stored; Cloud HSM is for customer-managed keys (CMEK).
- ✗
Set an organization policy to prevent Google from storing keys.
Why it's wrong here
No such organization policy exists; CSEK inherently does not store keys.
- ✗
Create a Cloud KMS key and use it as a CSEK.
Why it's wrong here
CSEK is separate from Cloud KMS; mixing them is incorrect.
Quick reference
Symmetric Encryption Algorithm Comparison
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCSE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCSE exam.