Google ACE Planning and Configuring a Cloud Solution Practice Question
An organization stores sensitive data in Cloud Storage. They need to ensure that objects are encrypted at rest using a key that they manage and rotate themselves. Which Cloud Storage encryption option should they use?
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 customer-managed encryption keys (CMEK)
Customer-managed encryption keys (CMEK) allow you to manage your own keys via Cloud KMS. Google-managed keys are default. Client-side encryption is done before upload. Supplied keys are also customer-provided but not managed via KMS.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Use customer-supplied encryption keys (CSEK)
Why it's wrong here
CSEK requires you to supply a raw AES key with every request to encrypt or decrypt an object, and Cloud Storage never stores that key. You are responsible for secure key storage, distribution, and rotation, with no built-in rotation schedule or centralized IAM policy management. Because the key is not integrated with Cloud KMS, rotating keys is a manual process that must be coordinated with your own infrastructure.
- ✓
Use customer-managed encryption keys (CMEK)
Why this is correct
CMEK lets you create and manage encryption keys in Cloud KMS, and Cloud Storage uses them to encrypt your objects server-side. You control the key lifecycle, including automatic rotation periods, and can grant or revoke access through IAM identities and conditions. This provides a central audit trail and the ability to disable or destroy keys instantly, which is exactly what the organization needs for sensitive data.
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Use client-side encryption
Why it's wrong here
Client-side encryption happens before any data is uploaded to Cloud Storage; you encrypt data in your own systems and manage the keys entirely outside Google Cloud's infrastructure. Cloud Storage never sees the plaintext or the keys, so features like object-level access evaluation, querying, or processing by other GCP services are ineffective. It also adds significant operational overhead for key distribution and rotation, and it is not a native Cloud Storage key management control.
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Use Google-managed encryption keys
Why it's wrong here
This is Cloud Storage's default server-side encryption, where Google owns and operates the entire key hierarchy from root key to per-object keys. You receive no visibility into key generation, rotation, or usage and cannot audit or control access to the keys themselves. While this offers strong security without management burden, it fails the requirement because the organization cannot enforce its own key rotation or compliance policies.
Go deeper
Related to this question
Learn chapter
Google Cloud Platform Overview
Key term
Cloud KMS
Cloud KMS (Key Management Service) is a cloud-based service that lets you create, manage, and use encryption keys to protect your data at rest and in transit.
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.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ACE 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 ACE exam.