The decrypt operation fails because the encryption context does not match the condition. AWS KMS requires that the encryption context supplied during decryption must be identical to the context used during encryption, and when a key policy enforces this with a `kms:EncryptionContextKeys` condition key, any mismatch—even with valid IAM permissions—causes the operation to be denied. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of how KMS encryption context conditions act as an additional authorization layer beyond IAM policies, often appearing as a trap where candidates assume that having `kms:Decrypt` permission alone guarantees success. The key insight is that the condition key checks for the presence and exact value of the context key, not just the permission. Remember the mnemonic: "Context must match—no match, no decrypt."
SCS-C02 Data Protection Practice Question
This SCS-C02 practice question tests your understanding of data protection. 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.
Refer to the exhibit. An AWS KMS key policy includes the statement shown. The AdminRole tries to decrypt a ciphertext that was encrypted using the same KMS key with encryption context 'department=engineering'. What will happen?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The decrypt operation fails because the encryption context does not match the condition.
Option D is correct because the KMS key policy includes a condition that requires the encryption context to match 'department=engineering'. When the AdminRole attempts to decrypt the ciphertext, the encryption context used during decryption must exactly match the context used during encryption. Since the policy enforces this condition with a kms:EncryptionContextKeys condition key, the decrypt operation fails if the context does not match, even though the role has kms:Decrypt permission.
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 decrypt operation succeeds because the role has kms:Decrypt permission.
Why it's wrong here
The condition must be satisfied, otherwise access is denied.
✗
The decrypt operation succeeds because the encryption context is ignored during decryption.
Why it's wrong here
Encryption context is used in authorization for KMS operations.
✗
The decrypt operation fails because the policy does not allow kms:Decrypt without matching context.
Why it's wrong here
Actually, the condition denies access when mismatched.
✓
The decrypt operation fails because the encryption context does not match the condition.
Why this is correct
The condition 'department=finance' is not met, so access is denied.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume kms:Decrypt permission alone is sufficient for decryption, overlooking that encryption context conditions in the key policy can override the permission and cause a failure even when the IAM role has the correct action allowed.
Detailed technical explanation
How to think about this question
AWS KMS uses encryption context as additional authenticated data (AAD) that is cryptographically bound to the ciphertext. The kms:EncryptionContextKeys condition key allows you to require that specific encryption context keys be present, and the kms:EncryptionContext condition key can enforce exact values. During decryption, the same encryption context must be provided; if it does not match, the decryption fails with a ValidationException. This is a common pattern for implementing fine-grained access control based on data classification or environment.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Data Protection — This question tests Data Protection — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The decrypt operation fails because the encryption context does not match the condition. — Option D is correct because the KMS key policy includes a condition that requires the encryption context to match 'department=engineering'. When the AdminRole attempts to decrypt the ciphertext, the encryption context used during decryption must exactly match the context used during encryption. Since the policy enforces this condition with a kms:EncryptionContextKeys condition key, the decrypt operation fails if the context does not match, even though the role has kms:Decrypt permission.
What should I do if I get this SCS-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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