SCS-C02 Data Protection Practice Question
A company wants to use client-side encryption for data uploaded to Amazon S3. The encryption keys must be managed by the company and never sent to AWS. Which S3 encryption option supports this requirement?
⚠ Common exam trap
Test-takers frequently confuse SSE-C with client-side encryption, not realizing that SSE-C still transmits the encryption key to AWS over the network, albeit encrypted in transit, which violates the 'never sent to AWS' requirement.
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
✓
Client-side encryption using the Amazon S3 encryption client.
Client-side encryption using the Amazon S3 encryption client is correct because the encryption process occurs entirely on the client side before data is uploaded to S3. The company manages the encryption keys locally and never transmits them to AWS, satisfying the requirement that keys are never sent to AWS.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Server-side encryption with AWS KMS (SSE-KMS).
Why it's wrong here
With SSE-KMS, Amazon S3 encrypts objects at rest using an AWS KMS key; S3 generates a data key and uses the KMS key to encrypt it, but the plaintext data key is held in S3's memory briefly to encrypt the object. This is a server-side mechanism, so the plaintext object is transmitted from the client to S3 over TLS before any encryption occurs, and AWS manages the key hierarchy. Therefore, it cannot satisfy a client-side encryption requirement where plaintext data and keys must never leave the customer's environment.
- ✓
Client-side encryption using the Amazon S3 encryption client.
Why this is correct
The Amazon S3 encryption client performs all cryptographic operations locally, encrypting the object's plaintext with a data key before anything is transmitted; the resulting ciphertext and an encrypted copy of the data key are then uploaded. The plaintext data key is never sent to AWS, and you can choose to wrap the data key with a KMS key or an internal master key that remains entirely under your control. This design is exactly what is needed when only the customer should ever possess the unencrypted form of the data.
- ✗
Server-side encryption with S3 managed keys (SSE-S3).
Why it's wrong here
SSE-S3 uses 256-bit AES encryption applied by S3 after the object is uploaded, but all key management—including the root keys and per-object data keys—is entirely handled by AWS. Since the data is uploaded as plaintext over HTTPS and only becomes encrypted once it reaches S3, AWS has access to the unencrypted content and the key material. This directly conflicts with a requirement that calls for client-side encryption, so it is not an appropriate choice.
- ✗
Server-side encryption with customer-provided keys (SSE-C).
Why it's wrong here
SSE-C lets you supply your own encryption key for each upload or download request, and S3 uses that key to encrypt/decrypt objects, discarding the key after processing. However, the key itself is transmitted to AWS with every request, meaning it is not retained from the client; this violates the fundamental client-side encryption requirement that key material never be exposed to AWS. Additionally, S3 temporarily holds the plaintext key in server memory to perform the cryptographic operation, making it distinct from true client-side encryption.
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
About these practice questions
Courseiva writes every SCS-C02 question from scratch — 1,205 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.