Question 21 of 1,616
Development with AWS ServiceseasyMultiple SelectObjective-mapped

Configuring SSE-KMS on S3: IAM Permissions and Bucket Policy

This DVA-C02 practice question tests your understanding of development with aws services. 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 Amazon S3 to store sensitive data. The security team requires that all data be encrypted at rest. The developer must implement a solution that uses server-side encryption with AWS KMS managed keys (SSE-KMS). Which TWO steps are required to meet this requirement? (Choose TWO.)

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

Grant the IAM role used by the application the kms:GenerateDataKey permission for the KMS key.

Option A is correct because SSE-KMS requires the application to have permission to call kms:GenerateDataKey to request a data key from AWS KMS for encrypting objects. Without this permission, the application cannot use the KMS key to encrypt data at rest in S3, fulfilling the security team's requirement for server-side encryption with AWS KMS managed keys.

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.

  • Grant the IAM role used by the application the kms:GenerateDataKey permission for the KMS key.

    Why this is correct

    To use SSE-KMS, the caller needs permission to generate data keys.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Set the default encryption on the S3 bucket to SSE-KMS and disable the option to override it.

    Why it's wrong here

    Default encryption can be overridden by each PUT request; bucket policy is needed to enforce encryption.

  • Set the x-amz-sse header to 'aws:kms' when uploading objects.

    Why it's wrong here

    The correct header is 'x-amz-server-side-encryption' with value 'aws:kms'.

  • Enable default encryption on the S3 bucket with SSE-S3.

    Why it's wrong here

    SSE-S3 uses Amazon S3 managed keys, not KMS. The requirement is SSE-KMS.

  • Configure an S3 bucket policy that denies PutObject requests if the request does not include the x-amz-server-side-encryption header.

    Why this is correct

    This enforces SSE-KMS for all uploads.

    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 confuse SSE-KMS with SSE-S3 or think that setting default encryption alone is sufficient, but the exam requires understanding that SSE-KMS demands explicit IAM permissions (kms:GenerateDataKey) and can be enforced via bucket policies (denying PutObject without the correct encryption header).

Detailed technical explanation

How to think about this question

SSE-KMS uses envelope encryption where S3 calls KMS to generate a data key (via GenerateDataKey) for each object, then encrypts the data key with the KMS key and stores it alongside the object. The kms:GenerateDataKey permission is distinct from kms:Encrypt and kms:Decrypt; it is specifically needed for S3 to obtain the plaintext and encrypted data key during upload. In real-world scenarios, misconfigured KMS key policies or missing kms:GenerateDataKey permissions are common causes of upload failures when enforcing SSE-KMS.

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.

Quick reference

AWS S3 Storage Class Comparison

Storage ClassMin DurationRetrievalUse Case
S3 StandardNoneImmediateFrequently accessed data
S3 Standard-IA30 daysImmediateInfrequent access, rapid retrieval
S3 One Zone-IA30 daysImmediateNon-critical infrequent data
S3 Intelligent-TieringNoneImmediate–hoursUnknown or changing access patterns
S3 Glacier Instant90 daysMillisecondsArchive with instant retrieval
S3 Glacier Flexible90 daysMinutes–hoursArchive, flexible retrieval
S3 Glacier Deep Archive180 daysHoursLong-term compliance archive

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.

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FAQ

Questions learners often ask

What does this DVA-C02 question test?

Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Grant the IAM role used by the application the kms:GenerateDataKey permission for the KMS key. — Option A is correct because SSE-KMS requires the application to have permission to call kms:GenerateDataKey to request a data key from AWS KMS for encrypting objects. Without this permission, the application cannot use the KMS key to encrypt data at rest in S3, fulfilling the security team's requirement for server-side encryption with AWS KMS managed keys.

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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Same concept, more angles

1 more ways this is tested on DVA-C02

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. A company is using Amazon S3 to store sensitive documents. The security team requires that all data be encrypted at rest using AWS KMS with a Customer Managed Key (CMK). The developer enabled default encryption on the S3 bucket with the CMK. However, some PUT requests are failing with 'Access Denied'. What is the MOST likely cause?

medium
  • A.The S3 bucket's object ownership is set to BucketOwnerPreferred.
  • B.The KMS key policy does not grant the IAM user/role permissions to use the key.
  • C.The KMS key is in a different AWS Region than the S3 bucket.
  • D.The S3 bucket policy denies PutObject without encryption.

Why B: When default encryption is enabled on an S3 bucket with a KMS CMK, the S3 service uses the CMK to encrypt objects at rest. However, the IAM user or role making the PUT request must have explicit permissions to use that CMK, typically via the kms:GenerateDataKey and kms:Decrypt actions in the KMS key policy. If the key policy does not grant these permissions to the principal, the request fails with an 'Access Denied' error, even though the bucket policy and IAM permissions are otherwise correct.

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Last reviewed: Jul 4, 2026

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This DVA-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 DVA-C02 exam.