hardMultiple ChoiceObjective-mapped
CISA Practice Question: Is developing a mobile app that will handle…
An organization is developing a mobile app that will handle personal health information (PHI). The security team mandates that data must be encrypted both in transit and at rest. Which of the following implementation strategies BEST ensures compliance?
⚠ Common exam trap
Candidates often confuse 'platform-level encryption' (Option C) as sufficient, but the CISA exam tests the understanding that platform encryption does not cover data in transit and may not meet specific regulatory requirements for application-layer encryption at rest.
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
✓
Implement TLS for data in transit and AES-256 encryption for data at rest
It uses TLS (the modern, secure successor to SSL) to encrypt data in transit, ensuring confidentiality and integrity during network communication, and AES-256, a strong symmetric encryption standard, to encrypt data at rest. This combination directly satisfies the mandate for encryption both in transit and at rest, as TLS protects against eavesdropping and tampering on the wire, while AES-256 protects stored PHI from unauthorized access if the device is lost or 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.
- ✗
Use HTTPS for all network communication and store data in plaintext
Why it's wrong here
Missing at-rest encryption.
- ✗
Use SSL and encrypt all data with a simple XOR cipher
Why it's wrong here
Weak encryption.
- ✗
Rely on platform-level encryption provided by the mobile OS
Why it's wrong here
May not be sufficient for PHI.
- ✓
Implement TLS for data in transit and AES-256 encryption for data at rest
Why this is correct
Covers both requirements.
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.