CAS-004 Security Architecture Practice Question
An organization is planning to modernize its cryptographic infrastructure to protect sensitive data for the next 10 years. The security architect must consider future threats from quantum computing. Which TWO quantum-resistant algorithms should the architect prioritize for key encapsulation and digital signatures? (Choose TWO.)
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
✓
CRYSTALS-Dilithium
CRYSTALS-Kyber is a key encapsulation mechanism (KEM), and CRYSTALS-Dilithium is a digital signature algorithm. Both are NIST PQC standards for post-quantum security. RSA and ECDSA are not quantum-resistant, and AES-256 is symmetric but does not provide key encapsulation or digital signatures.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
CRYSTALS-Dilithium
Why this is correct
CRYSTALS-Dilithium is a NIST-selected digital signature algorithm for post-quantum security.
- ✗
AES-256 with GCM
Why it's wrong here
AES-256 is a symmetric cipher and may have increased key size requirements but is not a KEM or signature algorithm.
- ✗
ECDSA with P-521
Why it's wrong here
Elliptic curve cryptography is susceptible to Shor's algorithm, making it non-quantum-resistant.
- ✗
RSA-4096
Why it's wrong here
RSA is vulnerable to quantum attacks and not considered quantum-resistant.
- ✓
CRYSTALS-Kyber
Why this is correct
CRYSTALS-Kyber is a NIST-selected KEM for post-quantum key exchange.
Quick reference
Symmetric Encryption Algorithm Comparison
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
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JA
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.