CAS-004 Security Engineering and Cryptography Practice Question
This CAS-004 practice question tests your understanding of security engineering and cryptography. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company is deploying a new authentication system that leverages FIDO2/WebAuthn. Security architects want to ensure that the private key never leaves the authenticator device. Which attack vector is mitigated by this approach?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "never"
Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Server-side database breach exposing credentials
FIDO2/WebAuthn uses public-key cryptography where the private key is generated on the authenticator and never exported. This prevents server-side database breaches from compromising private keys, as there are no shared secrets stored on the server.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Man-in-the-middle attacks on TLS
Why it's wrong here
TLS protects the channel, but FIDO2 does not directly mitigate MiTM on TLS.
✓
Server-side database breach exposing credentials
Why this is correct
Since no private keys or secrets are stored on the server, a breach does not expose authentication secrets.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Replay attacks on authentication tokens
Why it's wrong here
Replay attacks are mitigated by challenge-response, not by private key non-exportability.
✗
Phishing attacks
Why it's wrong here
While FIDO2 reduces phishing by binding credentials to origin, the key non-exportability specifically addresses server breaches.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CAS-004 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which CAS-004 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Security Engineering and Cryptography — This question tests Security Engineering and Cryptography — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Server-side database breach exposing credentials — FIDO2/WebAuthn uses public-key cryptography where the private key is generated on the authenticator and never exported. This prevents server-side database breaches from compromising private keys, as there are no shared secrets stored on the server.
What should I do if I get this CAS-004 question wrong?
Identify which CAS-004 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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