CISA Protection of Information Assets Practice Question
An IS auditor is evaluating the encryption key management program of a healthcare organization that processes protected health information (PHI). The organization uses a mix of symmetric and asymmetric keys. Which TWO of the following are key management practices that should be addressed to ensure effective protection of PHI?
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
✓
Storing encryption keys in a hardware security module (HSM)
Effective key management includes secure key storage (e.g., HSM) and regular key rotation to limit exposure. Key escrow is not a standard requirement, and distributing keys with data increases risk. Using a single key for all data violates best practices.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Storing encryption keys in a hardware security module (HSM)
Why this is correct
HSMs provide tamper-resistant storage for keys.
- ✗
Implementing a key escrow mechanism for all keys
Why it's wrong here
Key escrow is not a universal requirement and may introduce risk.
- ✗
Using the same key to encrypt all PHI for simplicity
Why it's wrong here
Using a single key violates the principle of least privilege and increases risk.
- ✗
Distributing keys to authorized users along with encrypted data
Why it's wrong here
Distributing keys with data undermines encryption.
- ✓
Rotating keys on a periodic basis or after a security incident
Why this is correct
Rotating keys periodically or after a security incident directly addresses the requirement to protect PHI under the principle of cryptographic agility, satisfying the healthcare organisation’s need to limit the exposure window of any compromised key. In a mixed symmetric/asymmetric environment, periodic rotation ensures that even if a private key or symmetric key is leaked, the ciphertext encrypted under the old key is no longer decryptable with the current key, thereby maintaining the confidentiality and integrity of PHI in compliance with HIPAA security standards.
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.