CAS-004 Security Engineering Practice Question
A security architect is designing a secure OTA update mechanism for IoT devices. Which TWO features are essential to ensure the integrity and authenticity of firmware updates?
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
✓
Secure boot chain that verifies the signature of the update before installation
Digital signatures ensure authenticity and integrity; a secure boot chain verifies the signature before executing the update, preventing unauthorized firmware.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Firmware encryption with AES-256-CTR
Why it's wrong here
Encryption provides confidentiality, not integrity/authenticity.
- ✓
Secure boot chain that verifies the signature of the update before installation
Why this is correct
Secure boot ensures that only signed updates are installed.
- ✗
Use of a hardware security module (HSM) on the device for key storage
Why it's wrong here
While good for key protection, it does not directly ensure integrity/authenticity of the update.
- ✗
Compression of the firmware image to reduce transfer size
Why it's wrong here
Compression does not provide security.
- ✓
Digital signature using ECDSA P-384
Why this is correct
Digital signatures provide authenticity and integrity.
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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.