Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.
For AWS DVA-C02 candidates, the confusion often lies in how to enforce server-side encryption on objects uploaded via the S3 PutObject API. In production, it’s crucial to know exactly which HTTP headers trigger SSE-S3 encryption and which do not. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
BrightTech Solutions is building a new microservice that ingests user-uploaded content and stores it in an Amazon S3 bucket. This service interacts with S3 via the HTTP PutObject API. The security team mandates all objects at rest in the bucket must be encrypted using server-side encryption with Amazon S3 managed keys (SSE-S3). The development team must implement this encryption mechanism while minimizing operational overhead and complexity.
The Requirement: #
Enable server-side encryption of objects stored in the S3 bucket using SSE-S3, triggered programmatically during upload via the PutObject API.
The Options #
- A) Create an AWS Key Management Service (AWS KMS) customer-managed key and assign the key policy to the S3 bucket.
- B) Set the
x-amz-server-side-encryptionHTTP header toAES256when calling the PutObject API. - C) Provide the encryption key in the HTTP header of every request for the PutObject operation.
- D) Use TLS (HTTPS) to encrypt data in transit from the application to the S3 bucket.
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Correct Answer #
B
Quick Insight: The Developer Imperative #
When using SSE-S3, AWS requires the client to specify the
x-amz-server-side-encryptionheader with the valueAES256during object upload. This explicitly instructs S3 to encrypt the object at rest using Amazon S3 managed keys.Creating a KMS key (Option A) is not required for SSE-S3; that is for SSE-KMS. Providing encryption keys in request headers (Option C) relates to client-side encryption, which is different from server-side encryption. TLS (Option D) secures data in transit only and does not handle encryption at rest.
Content Locked: The Expert Analysis #
You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?
The Expert’s Analysis #
Correct Answer #
Option B
The Winning Logic #
Specifying the x-amz-server-side-encryption header with the value AES256 on the PutObject API call explicitly enables SSE-S3 encryption for that object. This is the native, documented way to tell S3 to encrypt the data at rest using its fully managed keys, without having to manage your own KMS keys.
Options explanation:
-
Option A: While creating a KMS key is necessary for SSE-KMS, it is unnecessary for SSE-S3 which uses Amazon-managed keys. Also, assigning a KMS key to a bucket itself does not automatically encrypt all objects. This option confuses SSE-S3 with SSE-KMS.
-
Option C: Providing the encryption key in HTTP headers is relevant to client-side encryption where encryption/decryption is done by the client. This is different from server-side encryption and would require client-side key management — which the question explicitly excludes.
-
Option D: TLS encrypts data in transit and is always recommended, but it does not provide encryption of objects at rest in S3. This option addresses a different security layer and does not satisfy the encryption-at-rest requirement.
The Trap (Distractor Analysis): #
-
Why not A? Because KMS keys are only needed for SSE-KMS, not SSE-S3. Misapplying KMS often leads to unnecessary complexity and cost, which is a frequent pitfall.
-
Why not C? Because this approach corresponds to client-side encryption, which requires additional complexity that is not asked here.
-
Why not D? Because TLS affects encryption in transit, not at rest. This is a classic “security misalignment” distractor.
The Technical Blueprint #
# Example AWS CLI PutObject command enabling SSE-S3 encryption
aws s3api put-object \
--bucket brighttech-content-bucket \
--key user-uploads/photo.jpg \
--body ./photo.jpg \
--server-side-encryption AES256
This command adds the required x-amz-server-side-encryption: AES256 header implicitly, fulfilling the encryption at rest mandate.
The Comparative Analysis #
| Option | API Complexity | Performance Impact | Use Case |
|---|---|---|---|
| A | High (requires KMS setup) | Moderate | SSE-KMS server-side encryption |
| B | Low (header flag only) | None | SSE-S3 default encryption |
| C | Very High (client-side key management) | Potential latency increase | Client-side encryption (not requested) |
| D | None | None | Encryption in transit only |
Real-World Application (Practitioner Insight) #
Exam Rule #
For the exam, always pick setting the x-amz-server-side-encryption header to AES256 when you see SSE-S3 mentioned.
Real World #
In practice, many teams move beyond SSE-S3 to SSE-KMS for more granular control, audit trails, and compliance, but that comes with additional setup.
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the AWS DVA-C02 exam.