Google PCA Design for security and compliance Practice Question
A startup wants to encrypt data at rest in Cloud Storage using Customer-Managed Encryption Keys (CMEK). They have already created a Cloud KMS key ring and key. What additional step is required to enable CMEK for a new Cloud Storage bucket?
⚠ Common exam trap
A common misconception is that enabling the Cloud KMS API or using Cloud HSM is required for CMEK, when the actual critical step is granting the Cloud KMS CryptoKey Encrypter/Decrypter role to the Cloud Storage service account on the key.
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
✓
Grant the Cloud Storage service account the Cloud KMS CryptoKey Encrypter/Decrypter role on the key.
To use CMEK with Cloud Storage, the Cloud Storage service account must be granted the Cloud KMS CryptoKey Encrypter/Decrypter role on the specific key. This permission allows the bucket's underlying storage system to encrypt and decrypt objects using the customer-managed key. Without this IAM binding, the bucket cannot access the key, and CMEK operations will fail.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Enable the Cloud KMS API in the project where the bucket will reside.
Why it's wrong here
The Cloud KMS API should already be enabled if a key was created; it is not a separate step for the bucket.
- ✗
Create a Cloud HSM key instead, as CMEK requires HSM.
Why it's wrong here
CMEK can use software keys; HSM is a separate option.
- ✗
Add a label to the key ring to associate it with the bucket.
Why it's wrong here
Labels are optional metadata and do not affect encryption permissions.
- ✓
Grant the Cloud Storage service account the Cloud KMS CryptoKey Encrypter/Decrypter role on the key.
Why this is correct
The service account that Cloud Storage uses must be authorized to use the key.
Go deeper
Related to this question
Learn chapter
Introduction to Google Cloud Platform
Key term
Cloud storage
Cloud storage is a service that lets you save data on remote servers accessed over the internet instead of on your computer's hard drive.
Key term
Service
A service is a software component or system that performs a specific function and is available to be used by other programs or users over a network.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCA 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 PCA exam.