SCS-C02 SSE-S3 Practice Question
A company needs to protect data at rest in Amazon S3. Which THREE server-side encryption mechanisms can be used to encrypt objects stored in S3?
⚠ Common exam trap
SCS-C02 often tests whether candidates confuse client-side encryption with server-side options or invent non-existent mechanisms like SSE-IAM — the trap is picking 'client-side' as a server-side method or selecting a fabricated acronym.
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
✓
Server-Side Encryption with S3-Managed Keys (SSE-S3)
The question asks for server-side encryption mechanisms for S3 objects, and three options qualify. Option A, SSE-S3, is correct because Amazon S3 manages the encryption keys and applies AES-256 encryption to objects at rest, requiring only the x-amz-server-side-encryption: AES256 header. Option B, SSE-KMS, is correct because it uses AWS KMS customer master keys (CMKs) to generate and manage data keys, providing auditability via CloudTrail and granular key policies. Option E, SSE-C, is correct because the customer supplies their own encryption key with each request, and S3 performs the encryption/decryption server-side without storing the key. Option C, Client-Side Encryption, is not a server-side mechanism since data is encrypted before it reaches S3. Option D, SSE-IAM, does not exist as an S3 encryption option; IAM manages permissions, not encryption keys.
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 S3-Managed Keys (SSE-S3)
Why this is correct
SSE-S3 encrypts each object with a unique key, itself encrypted by a regularly rotated root key managed entirely by AWS, using AES-256. It satisfies data-at-rest protection with no key management overhead, applied by default to every uploaded object.
- ✓
Server-Side Encryption with AWS KMS-Managed Keys (SSE-KMS)
Why this is correct
SSE-KMS encrypts objects using keys managed in AWS KMS, giving granular key policies, audit trails via CloudTrail, and separation of duties. It satisfies data-at-rest protection while letting the customer control key rotation and access independently of S3.
- ✗
Client-Side Encryption
Why it's wrong here
Client-side encryption happens before objects reach AWS, so S3 stores only ciphertext and no server-side mechanism is applied. It is tempting because it protects data at rest, and would be correct where the organisation must retain sole custody of keys and AWS must never see plaintext.
- ✗
Server-Side Encryption with IAM-Managed Keys (SSE-IAM)
Why it's wrong here
No such mechanism exists; S3 server-side options are SSE-S3, SSE-KMS and SSE-C, with IAM policies governing key access rather than an IAM-managed key type. It is tempting because IAM controls access to KMS keys, and would be right if the stem asked how key usage is authorised.
- ✓
Server-Side Encryption with Customer-Provided Keys (SSE-C)
Why this is correct
SSE-C encrypts objects with keys the customer supplies on each request; AWS never stores the key, only a salted HMAC to verify it. This satisfies data-at-rest protection while retaining sole custody of the encryption key outside AWS.
Quick reference
Symmetric Encryption Algorithm Comparison
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
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One of 1,205 original SCS-C02 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
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.