DEA-C01 Data Security and Governance Practice Question
A data engineer needs to share a dataset stored in an Amazon S3 bucket with another AWS account. The dataset must remain encrypted at rest using AWS KMS. The data engineer creates a bucket policy that grants the other account access to the bucket. However, the other account reports that objects appear encrypted and they cannot decrypt them. What is the most likely cause?
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
✓
The KMS key policy does not grant the other account the kms:Decrypt permission
When using SSE-KMS, the bucket policy alone is not enough; the KMS key policy must also grant the consuming account permission to use the key (kms:Decrypt). The bucket policy controls access to the S3 objects, but KMS key policy controls who can decrypt. Therefore, option A is correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The KMS key policy does not grant the other account the kms:Decrypt permission
Why this is correct
Without decrypt permission on the KMS key, the other account cannot decrypt the objects even if they can download them.
- ✗
The bucket policy does not grant the s3:GetObject permission
Why it's wrong here
The question states the bucket policy grants access, so s3:GetObject is likely included. The issue is decryption.
- ✗
The other account must use the same KMS key to upload objects
Why it's wrong here
They need decrypt permission, not necessarily to use the same key for uploads.
- ✗
The objects are encrypted with SSE-S3, which is not supported for cross-account access
Why it's wrong here
SSE-S3 works for cross-account access; the encrypting account manages the 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 |
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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.