SCS-C02 Data Protection Practice Question
A company uses AWS KMS to encrypt data in Amazon S3. The security team wants to ensure that only users from a specific AWS account can decrypt objects. Which TWO steps should be taken to achieve this?
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
✓
Configure the KMS key policy to allow the target AWS account to use the key for decrypt.
Options B and D are correct. To allow decryption by a specific AWS account, you must configure the KMS key policy to grant the target account permission to use the key for decrypt (option B). Additionally, the target account must create an IAM policy that allows its users to call the kms:Decrypt action (option D). Option A is incorrect because S3 bucket policies cannot grant KMS decryption permissions; they only control S3 operations. Option C is incorrect because using a separate KMS key per object adds unnecessary complexity and does not solve the cross-account requirement. Option E is incorrect because enabling S3 default encryption with a KMS key does not restrict decryption to a specific account; it only ensures encryption is applied.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Add a bucket policy that denies decrypt for all users except those from the target account.
Why it's wrong here
S3 bucket policies cannot grant KMS decryption permissions; they only control S3 operations.
- ✓
Configure the KMS key policy to allow the target AWS account to use the key for decrypt.
Why this is correct
KMS key policy must allow the target account to use the key for decrypt.
- ✗
Use a different KMS key for each object to isolate permissions.
Why it's wrong here
Using a separate KMS key per object adds unnecessary complexity and does not solve the cross-account requirement.
- ✓
Create an IAM policy in the target account that allows the kms:Decrypt action.
Why this is correct
The target account must create an IAM policy that allows its users to call kms:Decrypt.
- ✗
Enable S3 default encryption with the KMS key.
Why it's wrong here
Enabling S3 default encryption with a KMS key does not restrict decryption to a specific account; it only ensures encryption is applied.
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 SCS-C02 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 SCS-C02 exam.