S3 Encryption at Rest: Choosing the Right Option
A company is designing a new application that will store sensitive data in Amazon S3. The data must be encrypted at rest using a key that is rotated every 90 days. The company wants to use AWS managed services to minimize operational overhead. Which encryption solution should they choose?
Quick Answer
The answer is SSE-S3, because it is the only S3 encryption option that provides automatic key rotation with zero operational overhead. SSE-S3 uses Amazon S3-managed keys that are rotated on a regular basis—typically every 90 days—without any action required from the customer, making it the ideal choice when the requirement is to minimize management burden while ensuring encryption at rest. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this question tests your understanding of the key management responsibilities for each encryption option: SSE-S3 offloads key rotation entirely to AWS, SSE-KMS offers automatic rotation but requires you to enable it and manage the KMS key policy, SSE-C puts key rotation on you, and client-side encryption adds significant operational complexity. A common trap is assuming SSE-KMS is always the best choice for automatic rotation, but the key distinction is that SSE-S3 rotates keys without any customer configuration. Memory tip: think "S3-managed = set and forget" for automatic rotation.
⚠ Common exam trap
Candidates often assume SSE-KMS with automatic rotation meets the 90-day requirement, but KMS automatic rotation is fixed at 365 days and cannot be changed, making SSE-S3 the only correct choice for a 90-day rotation policy with zero operational overhead.
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-S3
SSE-S3 (Amazon S3 managed keys) provides encryption at rest with automatic key rotation every 90 days, meeting the requirement without any operational overhead. The company wants AWS managed services to minimize operational overhead, and SSE-S3 handles key management and rotation entirely on the customer's behalf, with no configuration needed.
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-C
Why it's wrong here
SSE-C requires the customer to manage and rotate keys, increasing operational overhead.
- ✓
SSE-S3
Why this is correct
SSE-S3 automatically rotates keys every 90 days with no customer management.
- ✗
Client-side encryption with AWS KMS
Why it's wrong here
Client-side encryption adds complexity and operational overhead for key management.
- ✗
SSE-KMS with automatic rotation
Why it's wrong here
KMS can automatically rotate keys, but requires customer key management and may incur additional costs.
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
Related to this question
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Same concept, more angles
2 more ways this is tested on SAP-C02
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 company is designing a new application that will process sensitive financial data. They need to ensure encryption at rest and in transit. Which of the following should they use? (Select TWO.)
medium- ✓ A.TLS for all data in transit
- B.AWS Certificate Manager (ACM) for all encryption
- C.SSL certificates for all connections
- ✓ D.AWS Key Management Service (KMS) for encryption at rest
- E.AWS Identity and Access Management (IAM) for data encryption
Why A: TLS (Transport Layer Security) is the industry-standard protocol for encrypting data in transit, ensuring confidentiality and integrity between client and server. AWS services like ELB, CloudFront, and API Gateway enforce TLS for all communications, making it the correct choice for securing data in transit.
Variation 2. A company is designing a new application that will process sensitive financial data. They need to ensure that data at rest is encrypted using customer-provided encryption keys (SSE-C) in Amazon S3. Which action is required to enable this?
hard- A.Use AWS KMS to generate a key
- B.Enable default encryption on the bucket
- ✓ C.Provide the encryption key in the request headers
- D.Configure a bucket policy to require SSE-C
Why C: SSE-C requires the customer to provide the encryption key in the request headers when uploading or accessing objects. Amazon S3 uses the provided key to encrypt data at rest and then discards the key; the customer is responsible for managing the key lifecycle. This is the only way to enforce customer-provided encryption keys at the object level.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAP-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 SAP-C02 exam.