CAS-004 Security Engineering Practice Question
During a security audit, it was discovered that an application uses RSA with 1024-bit keys for encrypting sensitive data. The organization's security policy mandates a minimum of 128-bit symmetric equivalent security. Which of the following should be recommended as a replacement?
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
✓
RSA with 3072-bit keys
RSA 2048 provides approximately 112-bit security, while RSA 3072 provides 128-bit. AES-256-GCM is symmetric, not asymmetric. ECDSA is for signatures, not encryption. So RSA 3072 is the correct choice.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
RSA with 3072-bit keys
Why this is correct
RSA 3072 provides 128-bit security, meeting the requirement.
- ✗
AES-256-GCM
Why it's wrong here
AES-256-GCM is a symmetric cipher, not an asymmetric replacement for RSA encryption.
- ✗
ECDSA P-384
Why it's wrong here
ECDSA is for digital signatures, not encryption.
- ✗
RSA with 2048-bit keys
Why it's wrong here
RSA 2048 provides about 112-bit security, below the 128-bit requirement.
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.