CISA Protection of Information Assets Practice Question
An IS auditor is reviewing an organization's key management program. Which of the following is the GREATEST risk associated with using a single key for both encryption and decryption of sensitive data?
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
✓
Key rotation requires re-encrypting all data encrypted with that key.
Symmetric keys must be protected; if compromised, both confidentiality and integrity are at risk. However, the primary risk is the inability to rotate keys without re-encrypting all data, leading to potential exposure if the key is compromised.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The key management system cannot generate such a key.
Why it's wrong here
Systems can generate symmetric keys.
- ✗
The key may be more easily guessed by attackers.
Why it's wrong here
Key strength is independent of usage.
- ✗
Non-repudiation cannot be achieved.
Why it's wrong here
Non-repudiation is related to digital signatures, not encryption keys.
- ✓
Key rotation requires re-encrypting all data encrypted with that key.
Why this is correct
This operational difficulty may lead to prolonged use of a compromised key.
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 CISA practice question is part of Courseiva's free ISACA 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 CISA exam.