DEA-C01 Data Security and Governance Practice Question
A data engineer is configuring an S3 bucket for storing sensitive customer data. The bucket must be encrypted at rest using an AWS Key Management Service (KMS) key that is managed by the data engineering team. The team wants to ensure that only users with explicit permission can decrypt the data. Which S3 encryption option should be used?
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
✓
SSE-KMS
SSE-KMS is the correct option because it uses a customer-managed AWS KMS key, allowing the data engineering team to control access and permissions for decryption. Client-side encryption is not an S3 server-side encryption option and does not use KMS. SSE-S3 uses Amazon S3-managed keys, which do not provide customer-controlled access. SSE-C requires the customer to manage their own encryption keys and does not use KMS, nor does it allow the same level of access control as a CMK.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
SSE-KMS
Why this is correct
SSE-KMS encrypts objects with a KMS key, and decryption requires kms:Decrypt permission on that key. This satisfies the requirement for team-managed keys and explicit decrypt authorisation, unlike SSE-S3 where AWS owns the key and access is governed solely by S3 permissions.
- ✗
Client-side encryption
Why it's wrong here
Client-side encryption encrypts data before upload, so the KMS key never protects the S3 object at rest and AWS cannot enforce key-based decrypt permissions. It suits scenarios where the customer manages the entire encryption stack outside AWS. The stem requires an AWS KMS key managed by the team, which client-side encryption does not use.
- ✗
SSE-S3
Why it's wrong here
SSE-S3 uses Amazon S3-managed keys, not a KMS key the data engineering team owns, so key policies cannot restrict decryption to explicitly permitted users. It suits general-purpose encryption where key management is delegated to AWS. The stem requires a customer-managed KMS key with explicit decrypt permissions.
- ✗
SSE-C
Why it's wrong here
SSE-C requires the customer to supply the encryption key with every request; that key is never stored in AWS KMS, so the team cannot manage it there or control decryption through KMS key policies. It fits scenarios where you retain sole custody of keys outside AWS. The stem mandates a KMS-managed key.
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 |
Go deeper
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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 is configuring an S3 bucket to host sensitive data. The security policy requires that all objects be encrypted with a key that is generated and managed by the customer, and that the key be stored in AWS KMS. Which encryption option should be used?
medium- A.Server-Side Encryption with S3-Managed Keys (SSE-S3)
- B.Client-Side Encryption
- C.Server-Side Encryption with Customer-Provided Keys (SSE-C)
- ✓ D.Server-Side Encryption with AWS KMS-Managed Keys (SSE-KMS)
Why D: SSE-KMS allows you to use customer-managed keys stored in AWS KMS, meeting the requirement for customer-generated and managed keys. Option A is incorrect because SSE-S3 uses AWS-managed keys, not customer-managed. Option B is incorrect because client-side encryption encrypts data outside S3, not using S3 server-side encryption. Option C is incorrect because SSE-C uses customer-provided keys that you manage yourself, but they are not stored in AWS KMS—you must provide them with each request.
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.