SSCP Cryptography Practice Question
A security auditor reviews a system that uses HMAC-SHA256 for message authentication. Which property does HMAC provide that a simple hash of the message does not?
⚠ Common exam trap
Watch out — candidates often confuse integrity (provided by any hash) with authentication (which requires a shared secret), leading them to think a simple hash is sufficient for message authentication, but HMAC specifically adds the keyed property.
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
✓
Integrity and authentication using a shared secret
HMAC-SHA256 uses a shared secret key combined with the message before hashing, which provides both integrity (detecting tampering) and authentication (verifying the sender knows the secret). A simple hash of the message alone offers integrity but no authentication, because anyone can compute the same hash without a secret. Thus, HMAC adds authentication via the shared secret, making option C correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Confidentiality
Why it's wrong here
HMAC-SHA256 outputs a tag computed over the message and key; the message itself remains readable, so confidentiality is not provided. Confidentiality requires encryption such as AES. HMAC is selected when verifying integrity and authenticity of a message whose contents need not be hidden.
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Non-repudiation
Why it's wrong here
HMAC uses a shared symmetric key, so both parties can compute the same tag; either could forge it, meaning no third party can attribute a message to one sender. Non-repudiation requires asymmetric signing with a private key. HMAC is chosen for integrity and authenticity between parties sharing a secret.
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Integrity and authentication using a shared secret
Why this is correct
HMAC mixes the message with a shared secret key before hashing, so it verifies both integrity and origin authenticity between parties holding that key. A plain hash provides integrity checking only, and anyone can recompute it, giving no authentication.
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Forward secrecy
Why it's wrong here
Forward secrecy protects past session keys if a long-term key is later compromised, achieved through ephemeral Diffie-Hellman key exchange. HMAC-SHA256 only produces a keyed message authentication tag; it performs no key agreement or session key derivation, so it cannot deliver this property.
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Same concept, more angles
1 more way this is tested on SSCP
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which of the following best describes the difference between HMAC and a simple hash function like SHA-256 when used for message authentication?
hard- A.HMAC is faster than SHA-256
- B.SHA-256 produces a larger digest than HMAC
- ✓ C.HMAC provides integrity and authentication; SHA-256 provides only integrity
- D.HMAC is used for encryption, not hashing
Why C: HMAC incorporates a secret key into the hash process, providing authentication that a simple hash cannot.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SSCP practice question is part of Courseiva's free ISC2 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 SSCP exam.