The answer is a JWT signature validation key mismatch, where the token was signed with a different secret key than the one used by the verifier. This is the most likely cause because JSON Web Token authentication relies on the verifier possessing the exact same secret key (for HMAC) or the corresponding public key (for RSA/ECDSA) to validate the signature; any discrepancy between the signing key and the verification key will produce a signature validation failure, as shown in the error logs. On the CISSP exam, this scenario tests your understanding of cryptographic key management and secure token lifecycle, often appearing in questions about authentication failures after key rotation or misconfiguration. A common trap is to blame token expiration or user error, but the clue is the "new token" that suddenly fails—pointing to a key mismatch rather than a time-based issue. Remember the mnemonic: "Same sign, same key; mismatch means mismatch."
CISSP Identity and Access Management Practice Question
This CISSP practice question tests your understanding of identity and access management. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Exhibit
Refer to the exhibit.
Error Log:
2024-05-20 14:23:01 ERROR [com.example.auth] Authentication failed for user 'jsmith' from IP 192.168.1.100: Invalid token signature
2024-05-20 14:23:01 ERROR [com.example.auth] Token validation failed: JWT signature does not match locally computed signature
Refer to the exhibit. A user reports they cannot authenticate to a web application after receiving a new token. The error log shows the above entries. Which of the following is the MOST likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Refer to the exhibit.
Error Log:
2024-05-20 14:23:01 ERROR [com.example.auth] Authentication failed for user 'jsmith' from IP 192.168.1.100: Invalid token signature
2024-05-20 14:23:01 ERROR [com.example.auth] Token validation failed: JWT signature does not match locally computed signature
A
The token uses a different signing algorithm than expected
Why wrong: Would show 'unexpected algorithm' error.
B
The token has expired
Why wrong: Would show 'token expired' error, not signature mismatch.
C
The token's issuer claim does not match the expected issuer
Why wrong: Would show 'invalid issuer' error.
D
The token was signed with a different secret key than the one used by the verifier
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The token was signed with a different secret key than the one used by the verifier
The error log entries indicate a signature validation failure, which occurs when the token was signed with a secret key that differs from the one the verifier uses. In JSON Web Token (JWT) authentication, the verifier must possess the exact same secret (for HMAC) or the corresponding public key (for RSA/ECDSA) to validate the signature; a mismatch causes authentication to fail. This is the most likely cause because the user received a new token, suggesting a key rotation or misconfiguration where the signing key was changed without updating the verifier.
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.
✗
The token uses a different signing algorithm than expected
Why it's wrong here
Would show 'unexpected algorithm' error.
✗
The token has expired
Why it's wrong here
Would show 'token expired' error, not signature mismatch.
✗
The token's issuer claim does not match the expected issuer
Why it's wrong here
Would show 'invalid issuer' error.
✓
The token was signed with a different secret key than the one used by the verifier
Why this is correct
Signature mismatch indicates key mismatch.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the distinction between signature validation failures (key mismatch) and claim validation failures (exp, iss, aud), and the trap here is that candidates confuse a token being 'invalid' with it being 'expired' or having a wrong issuer, when the error log specifically points to cryptographic signature failure.
Trap categories for this question
Command / output trap
Would show 'unexpected algorithm' error.
Detailed technical explanation
How to think about this question
In JWT validation per RFC 7519, the verifier must first check the 'alg' header to determine the cryptographic algorithm, then validate the signature using the key identified by the 'kid' (key ID) header or a pre-configured key. A common real-world scenario is key rotation where the token issuer starts signing with a new private key but the verifier's public key cache is stale, causing signature validation to fail until the verifier fetches the updated key. The error log entries showing 'signature verification failed' or 'invalid signature' are definitive indicators of a key mismatch, not a claim or algorithm issue.
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.
TExam Day Tips
→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 developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
Identity and Access Management — This question tests Identity and Access Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The token was signed with a different secret key than the one used by the verifier — The error log entries indicate a signature validation failure, which occurs when the token was signed with a secret key that differs from the one the verifier uses. In JSON Web Token (JWT) authentication, the verifier must possess the exact same secret (for HMAC) or the corresponding public key (for RSA/ECDSA) to validate the signature; a mismatch causes authentication to fail. This is the most likely cause because the user received a new token, suggesting a key rotation or misconfiguration where the signing key was changed without updating the verifier.
What should I do if I get this CISSP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This CISSP 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 CISSP exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.