- A
Create a bucket policy that denies s3:GetObject unless the request includes a specific encryption context
Why wrong: Bucket policy alone does not control decryption; key policy is needed.
- B
Modify the KMS key policy to allow only the authorized IAM roles to use the key
Key policy controls access to the key.
- C
Attach an IAM policy to the authorized users that grants kms:Decrypt on the CMK
Grants decryption permission on the key.
- D
Create a VPC endpoint for S3 and use bucket policies to restrict access to the endpoint
Why wrong: VPC endpoint policies do not control decryption.
- E
Use SSE-C with a customer-provided key
Why wrong: SSE-C is not a CMK in KMS.
Question 2 of 1,748
How to Control Decryption of S3 Objects Using IAM and KMS Key Policies
This SCS-C02 practice question tests your understanding of data protection. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 designing a data protection strategy for its Amazon S3 bucket that stores sensitive customer data. The bucket must be encrypted at rest using a customer managed key (CMK) that is stored in AWS KMS. The company also needs to ensure that only authorized users can decrypt objects. Which TWO actions should the company take?
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
✓
Modify the KMS key policy to allow only the authorized IAM roles to use the key
To control decryption of S3 objects encrypted with a CMK in KMS, you must grant kms:Decrypt permission to authorized users, typically via an IAM policy (option C). Additionally, the KMS key policy should be configured to allow only the authorized IAM roles to use the key (option B). Option A is incorrect because a bucket policy with encryption context conditions controls the encryption context during upload, not decryption. Option D is incorrect because a VPC endpoint for S3 restricts network access but does not grant decryption permissions. Option E is incorrect because SSE-C uses a customer-provided key, not a KMS CMK.
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.
- ✗
Create a bucket policy that denies s3:GetObject unless the request includes a specific encryption context
Why it's wrong here
Bucket policy alone does not control decryption; key policy is needed.
- ✓
Modify the KMS key policy to allow only the authorized IAM roles to use the key
Why this is correct
Key policy controls access to the key.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Attach an IAM policy to the authorized users that grants kms:Decrypt on the CMK
Why this is correct
Grants decryption permission on the key.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create a VPC endpoint for S3 and use bucket policies to restrict access to the endpoint
Why it's wrong here
VPC endpoint policies do not control decryption.
- ✗
Use SSE-C with a customer-provided key
Why it's wrong here
SSE-C is not a CMK in KMS.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
What to study next
Got this wrong? Here's your next step.
Identify which SCS-C02 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.
- →
Data Protection — study guide chapter
Learn the concepts, then practise the questions
- →
Data Protection practice questions
Targeted practice on this topic area only
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AWS Certified Security Specialty SCS-C02 study guide
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FAQ
Questions learners often ask
What does this SCS-C02 question test?
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: Modify the KMS key policy to allow only the authorized IAM roles to use the key — To control decryption of S3 objects encrypted with a CMK in KMS, you must grant kms:Decrypt permission to authorized users, typically via an IAM policy (option C). Additionally, the KMS key policy should be configured to allow only the authorized IAM roles to use the key (option B). Option A is incorrect because a bucket policy with encryption context conditions controls the encryption context during upload, not decryption. Option D is incorrect because a VPC endpoint for S3 restricts network access but does not grant decryption permissions. Option E is incorrect because SSE-C uses a customer-provided key, not a KMS CMK.
What should I do if I get this SCS-C02 question wrong?
Identify which SCS-C02 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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 20, 2026
This SCS-C02 practice question is part of Courseiva's free Amazon Web Services 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 SCS-C02 exam.
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