The answer is that two actions are required: the IAM user needs both the `s3:GetObject` permission on the bucket and the `kms:Decrypt` permission on the specific KMS key. This is because when an S3 object is encrypted with SSE-KMS, the GetObject request first retrieves the encrypted ciphertext from S3, then S3 calls KMS to decrypt the object key using the customer master key. Without `s3:GetObject`, the user cannot even initiate the request; without `kms:Decrypt`, the decryption step fails even if the object is retrieved. On the AWS Certified Developer Associate DVA-C02 exam, this tests your understanding that S3 and KMS permissions are separate but must both be granted—a common trap is thinking only KMS permissions are needed. Remember the memory tip: "Get it from S3, then Decrypt it with KMS"—two distinct API calls requiring two distinct permissions.
DVA-C02 Security Practice Question
This DVA-C02 practice question tests your understanding of security. 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.
A company is using AWS KMS to encrypt data in S3. Which TWO actions are required to allow an IAM user to decrypt objects in a specific S3 bucket?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Attach a policy to the user allowing s3:GetObject on the bucket.
Option A is correct because to decrypt an object stored in S3 using server-side encryption with AWS KMS (SSE-KMS), the IAM user must have the s3:GetObject permission to retrieve the encrypted object from the bucket. Without this permission, the user cannot even initiate the GetObject request, regardless of KMS permissions.
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.
✓
Attach a policy to the user allowing s3:GetObject on the bucket.
Why this is correct
Required to retrieve the object.
Related concept
Read the scenario before looking for a memorised answer.
✗
Attach a policy to the user allowing kms:Encrypt.
Why it's wrong here
Encryption not needed for decryption.
✗
Attach a policy to the user allowing s3:PutObject.
Why it's wrong here
Not needed for decryption.
✗
Attach a policy to the user allowing kms:GenerateDataKey.
Why it's wrong here
Not needed for decryption.
✓
Attach a policy to the user allowing kms:Decrypt on the KMS key.
Why this is correct
Required to decrypt the object.
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 often forget that decrypting an SSE-KMS encrypted object requires both S3 read permissions and KMS decrypt permissions, leading them to select only one of the two required actions.
Detailed technical explanation
How to think about this question
When S3 uses SSE-KMS, the GetObject call triggers S3 to send a Decrypt request to KMS using the KMS key specified in the object metadata. The IAM user must have both s3:GetObject on the bucket/object and kms:Decrypt on the specific KMS key; the KMS key policy must also grant the user or the IAM role access. Without the kms:Decrypt permission, S3 will return an access denied error even if s3:GetObject is allowed.
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 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.
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.
Security — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Attach a policy to the user allowing s3:GetObject on the bucket. — Option A is correct because to decrypt an object stored in S3 using server-side encryption with AWS KMS (SSE-KMS), the IAM user must have the s3:GetObject permission to retrieve the encrypted object from the bucket. Without this permission, the user cannot even initiate the GetObject request, regardless of KMS permissions.
What should I do if I get this DVA-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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