CAS-004 Security Architecture Practice Question
A healthcare organization is designing a new system to store patient records. The security architect must ensure that data at rest is encrypted and that cryptographic keys are rotated regularly without re-encrypting the entire database. Which of the following techniques should be used?
⚠ Common exam trap
The trap here is assuming that any encryption at rest supports easy key rotation, when in fact full-database encryption often requires re-encryption.
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
✓
Envelope encryption using a data encryption key (DEK) per record and a key encryption key (KEK) managed by a key management service (KMS).
Envelope encryption separates data encryption keys from key encryption keys. Each record is encrypted with a unique DEK, and the DEK is encrypted with a KEK. Rotating the KEK only requires re-encrypting the DEKs, not the data, enabling regular key rotation without massive re-encryption. This is efficient, scalable, and limits the blast radius of a compromised key, making it ideal for healthcare data with strict compliance.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Transparent data encryption (TDE) with a single certificate used to encrypt the database.
Why it's wrong here
TDE encrypts the entire database at the file level, but rotating the certificate typically requires re-encryption of the database or at least significant downtime. It does not provide granular key rotation per record. TDE protects data at rest but does not support the requirement of regular key rotation without re-encrypting the entire database.
- ✓
Envelope encryption using a data encryption key (DEK) per record and a key encryption key (KEK) managed by a key management service (KMS).
Why this is correct
Envelope encryption uses a DEK to encrypt each record and a KEK to encrypt the DEK. To rotate keys, only the KEK needs to be rotated, and the DEKs are re-encrypted with the new KEK, not the data itself. This allows regular key rotation without re-encrypting the entire database. It also limits the scope of a compromised DEK to a single record.
- ✗
Full database encryption with a single master key stored in a hardware security module (HSM).
Why it's wrong here
Full database encryption with a single master key encrypts all data, but rotating the master key would require re-encrypting the entire database, which is impractical for large datasets. This approach does not support efficient key rotation without re-encryption. It also creates a single point of failure if the master key is compromised.
- ✗
Column-level encryption using a static symmetric key stored in a configuration file.
Why it's wrong here
Column-level encryption encrypts specific columns, but using a static symmetric key stored in a configuration file is insecure and does not support key rotation. Rotating the key would require re-encrypting all affected columns. This approach lacks the centralized key management and rotation capabilities needed for compliance and security.
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.
Go deeper
Related to this question
About these practice questions
This CAS-005 question is part of Courseiva's 973-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
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.