hardMultiple ChoiceObjective-mapped
CAS-004 Practice Question: A security architect is evaluating a new cloud…
A security architect is evaluating a new cloud SaaS application that will handle sensitive customer data. The SaaS provider offers a shared responsibility model where the customer is responsible for data classification, access management, and encryption of data at rest using customer-managed keys. The architect must ensure that the organization retains the ability to revoke access to the data if the provider is compromised. Which key management strategy best meets this requirement?
⚠ Common exam trap
The CAS-004 exam often tests the misconception that using a provider's KMS or HSM (even with customer-managed keys) provides sufficient separation, but the trap is that any key stored within the provider's boundary can be accessed by the provider if their security is breached, whereas BYOK with an external KMS ensures true customer-only 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
✓
Implement bring-your-own-key (BYOK) with keys stored in a customer-controlled external KMS
BYOK with keys stored in a customer-controlled external KMS ensures the organization retains full control over encryption keys, enabling immediate revocation of access to data at rest if the SaaS provider is compromised. This aligns with the shared responsibility model where the customer manages keys, and external KMS decouples key management from the provider's infrastructure, preventing the provider from accessing data after key revocation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Escrow the encryption key with a third-party and rely on legal agreements for revocation
Why it's wrong here
Key escrow does not provide technical revocation capability; it relies on legal processes.
- ✗
Use the provider's default encryption with a customer-managed key stored in the provider's KMS
Why it's wrong here
The key is still managed by the provider's KMS, so revocation depends on the provider's controls.
- ✗
Use a cloud hardware security module (HSM) to generate and store keys
Why it's wrong here
While secure, the HSM is still within the provider's infrastructure; revocation may not be immediate.
- ✓
Implement bring-your-own-key (BYOK) with keys stored in a customer-controlled external KMS
Why this is correct
BYOK with external KMS gives the customer full control to revoke access immediately.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CAS-005 practice question is part of Courseiva's free CompTIA 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 CAS-005 exam.