DEA-C01 Data Security and Governance Practice Question
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?
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
✓
Server-Side Encryption with AWS KMS-Managed Keys (SSE-KMS)
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.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Server-Side Encryption with S3-Managed Keys (SSE-S3)
Why it's wrong here
SSE-S3 uses AWS-owned AES-256 keys that customers never generate or manage, so it cannot satisfy the requirement for a customer-managed key stored in AWS KMS. It is tempting because it is the default, zero-configuration option for basic at-rest encryption where no key control or audit trail is mandated.
- ✗
Client-Side Encryption
Why it's wrong here
Client-side encryption encrypts data before upload, with keys held outside AWS KMS by the customer's own tooling, so no KMS-stored key is used. It is tempting when the customer must retain sole custody of keys, but the policy explicitly requires the key to reside in AWS KMS.
- ✗
Server-Side Encryption with Customer-Provided Keys (SSE-C)
Why it's wrong here
SSE-C requires the customer to supply the encryption key with every request; AWS KMS never stores or manages that key, so the KMS-storage requirement fails. It is tempting when the customer wants full key custody without KMS, but here the key must live in AWS KMS.
- ✓
Server-Side Encryption with AWS KMS-Managed Keys (SSE-KMS)
Why this is correct
SSE-KMS encrypts objects using keys held in AWS KMS, and selecting a customer managed key means the customer generates and controls that key, including its policy and rotation. SSE-S3 uses AWS-owned keys the customer cannot manage.
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
2 more ways 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 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?
medium- ✓ A.SSE-KMS
- B.Client-side encryption
- C.SSE-S3
- D.SSE-C
Why A: 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.
Variation 2. A data engineer needs to ensure that an S3 bucket containing sensitive customer data is encrypted at rest. The company requires that all encryption keys be managed by AWS and rotated annually. Which encryption option meets these requirements?
medium- A.Use server-side encryption with AWS KMS (SSE-KMS)
- B.Use client-side encryption with AWS KMS
- C.Use server-side encryption with customer-provided keys (SSE-C)
- ✓ D.Use server-side encryption with S3-managed keys (SSE-S3)
Why D: SSE-S3 uses AWS-managed keys and automatically handles annual key rotation, meeting both requirements of encryption at rest and AWS-managed keys with rotation. SSE-KMS also uses AWS-managed keys but does not automatically rotate keys (unless using a custom KMS key with rotation enabled, but the question implies automatic rotation without extra configuration). SSE-C requires customer-provided keys, which violates the requirement that AWS manages the keys. Client-side encryption (B) is not server-side and also involves customer management. Thus, only SSE-S3 fully satisfies the requirements.
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.