DEA-C01 Data Security and Governance Practice Question
A company is using AWS KMS to encrypt data in Amazon S3. The security team wants to ensure that only specific IAM roles can decrypt the data. Which TWO steps should the data engineer take? (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
✓
Create a customer-managed KMS key with a key policy that grants kms:Decrypt only to the allowed IAM roles
To ensure only specific IAM roles can decrypt data in S3 using KMS, you must create a customer-managed KMS key with a key policy that grants kms:Decrypt only to those roles (C). Then, configure the S3 bucket to use SSE-KMS with that key (E). This restricts decryption to only the allowed roles because the key policy explicitly controls access. Option A uses the default AWS managed key which cannot be restricted to specific roles. Option B (SSE-S3) does not use KMS and hence cannot provide role-based decryption control. Option D, requiring MFA for decryption, adds an extra authentication factor but does not by itself restrict which roles can decrypt; it only strengthens the security of the roles that already have permission. Therefore, D is not a step to ensure only specific roles can decrypt.
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 the default AWS managed KMS key for S3 (aws/s3)
Why it's wrong here
Incorrect. The AWS managed key (aws/s3) is automatically available to the S3 service and does not allow role-based restrictions in its key policy.
- ✗
Use SSE-S3 encryption instead of KMS
Why it's wrong here
Incorrect. SSE-S3 uses S3-managed encryption keys, not KMS, so role-based decryption control is not possible.
- ✓
Create a customer-managed KMS key with a key policy that grants kms:Decrypt only to the allowed IAM roles
Why this is correct
Correct. The key policy on a customer-managed key can explicitly list which IAM roles are allowed to perform kms:Decrypt.
- ✗
Add an IAM policy to the role that requires MFA for kms:Decrypt
Why it's wrong here
Incorrect. Requiring MFA adds an extra condition for decryption but does not restrict which roles can decrypt; it only enhances security for roles that already have the permission.
- ✓
Configure the S3 bucket to use SSE-KMS with the customer-managed key
Why this is correct
Correct. Configuring the bucket to use SSE-KMS with the customer-managed key ensures that the key policy controls access.
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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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.