Which S3 Default Encryption Configuration Uses SSE-KMS with a Customer-Managed Key and Auto Rotation?
A data engineering team needs to encrypt data at rest in an Amazon S3 bucket that stores sensitive customer information. The team must use an AWS Key Management Service (AWS KMS) customer managed key with automatic rotation enabled. Which configuration meets these requirements?
Quick Answer
The correct configuration is to use default encryption with SSE-KMS and specify the customer managed key ID. This meets the requirement because SSE-KMS allows you to select a customer managed key, which gives you full control over key policies, usage, and automatic rotation—enabling you to set a rotation period of 90 days to one year. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your ability to distinguish between S3 encryption options, with a common trap being confusion between SSE-KMS with an AWS managed key (which you cannot control or rotate automatically) and a customer managed key. Remember that only customer managed keys support automatic rotation and granular access control. A helpful memory tip: “Customer controls rotation, AWS manages the default.”
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
✓
Use default encryption with SSE-KMS and specify the customer managed key ID.
It enables SSE-KMS with a customer managed key that supports automatic key rotation, meeting the requirement for a customer managed key with automatic rotation. Option B is incorrect because SSE-S3 uses AWS managed keys that are not customer-controlled and do not support automatic rotation. Option C is incorrect because SSE-C requires the customer to provide and manage their own keys, and does not support automatic rotation. Option D is incorrect because leaving the key ID empty defaults to the AWS managed KMS key, which is not a customer managed key and does not support automatic rotation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use default encryption with SSE-KMS and specify the customer managed key ID.
Why this is correct
SSE-KMS with a customer managed key allows automatic rotation and customer control.
- ✗
Use default encryption with SSE-S3.
Why it's wrong here
SSE-S3 uses AWS managed keys, not customer managed keys.
- ✗
Use default encryption with SSE-C and provide a customer-provided key.
Why it's wrong here
SSE-C does not support automatic key rotation.
- ✗
Use default encryption with SSE-KMS and leave the key ID empty to use the AWS managed key.
Why it's wrong here
AWS managed key does not provide customer control.
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 |
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Same concept, more angles
1 more way this is tested on DEA-C01
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 data engineer needs to encrypt data at rest in Amazon S3 using server-side encryption with a customer-managed KMS key. Which TWO steps are required to ensure that the KMS key can be used for S3 object encryption?
medium- A.Configure a VPC endpoint for KMS to allow S3 to access the key.
- B.Set the S3 bucket policy to require SSE-KMS for all PutObject requests.
- ✓ C.Add a statement in the KMS key policy that allows the S3 service to use the key.
- ✓ D.Grant the IAM role that writes objects the kms:GenerateDataKey and kms:Decrypt permissions.
- E.Create a service-linked role for S3 to access KMS.
Why C: Options C and D are correct. For SSE-KMS with a customer-managed key, the KMS key policy must include a statement that allows the S3 service to use the key (e.g., kms:GenerateDataKey and kms:Decrypt). Additionally, the IAM role writing objects must have kms:GenerateDataKey and kms:Decrypt permissions. Option A is not required because a VPC endpoint for KMS is not mandatory for S3 to access the key. Option B is not required because enforcing SSE-KMS via bucket policy is a separate configuration, not a prerequisite for using the key. Option E is not required because S3 does not use a service-linked role for KMS access.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-C01 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 DEA-C01 exam.