CAS-004 Security Architecture Practice Question
A security architect is designing a system that must provide confidentiality and integrity for data at rest and in transit. The organization wants to minimize the risk of key compromise and ensure that a single compromised key does not expose all data. Which key management strategy best meets these requirements?
⚠ Common exam trap
The trap here is assuming that storing a single master key in an HSM or a centralized vault is sufficient, when in fact it creates a single point of failure that violates the requirement for key isolation.
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 a hierarchical key management system with data encryption keys wrapped by key encryption keys
A hierarchical key management system with unique data encryption keys wrapped by key encryption keys ensures that compromise of one data key only affects the data it protects. This limits the blast radius and meets the requirement that a single compromised key does not expose all data. Other strategies create single points of failure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Derive all encryption keys from a single password using PBKDF2
Why it's wrong here
Deriving all keys from a single password means that compromise of that password compromises all derived keys. PBKDF2 strengthens the password against brute force but does not prevent a single point of failure. This approach fails to isolate data so that one compromised key does not expose everything.
- ✗
Use a single master key to encrypt all data, stored in a hardware security module (HSM)
Why it's wrong here
Using a single master key for all data creates a single point of failure; if that key is compromised, all data is exposed. While an HSM protects the key, the strategy violates the requirement that a single compromised key should not expose all data. Therefore, it does not meet the design goals.
- ✗
Store all encryption keys in a centralized key vault without additional wrapping
Why it's wrong here
A centralized key vault provides access control and auditing, but if the vault is compromised, all keys are exposed. Without wrapping or hierarchical separation, a single breach can compromise all data. This strategy does not minimize the risk of a single key compromise affecting the entire dataset.
- ✓
Implement a hierarchical key management system with data encryption keys wrapped by key encryption keys
Why this is correct
A hierarchical key management system uses unique data encryption keys (DEKs) for each data object or session, and wraps them with key encryption keys (KEKs). Compromise of one DEK exposes only the data it protects, not the entire dataset. This minimizes risk and meets the requirement that a single compromised key does not expose all data.
Quick reference
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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.