Quick Answer
The answer is SSE-C, SSE-KMS, and SSE-S3. These three methods for S3 encryption at rest are all valid because they each provide server-side encryption, meaning AWS encrypts the object before writing it to disk and decrypts it when you retrieve it, but they differ in key management. SSE-C gives you full control by letting you supply your own encryption keys in each request, which S3 uses and then discards, while SSE-KMS integrates with AWS Key Management Service for centralized key control and auditing, and SSE-S3 uses Amazon-managed keys with minimal configuration. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this topic tests your understanding of encryption responsibilities and compliance requirements; a common trap is confusing SSE-C with client-side encryption or assuming SSE-S3 is insufficient for sensitive data. Remember the mnemonic “Three S’s for S3: S3, KMS, and Customer Keys” to recall that all three server-side options are valid for encryption at rest.
This SAP-C02 practice question tests your understanding of design for new solutions. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company is designing a new system that will use Amazon S3 to store sensitive data. Which THREE methods can be used to encrypt data at rest in S3?
SSE-C
Server-side encryption with customer-provided keys.
Client-side encryption
Why wrong: Not a built-in S3 encryption method; done on client side.
SSE-S3
Server-side encryption with S3-managed keys.
SSE-KMS
Server-side encryption with KMS-managed keys.
AWS IAM
Why wrong: IAM is for access control, not encryption.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
SSE-C
SSE-C (Server-Side Encryption with Customer-Provided Keys) is correct because it allows you to encrypt data at rest in S3 using your own encryption keys, which you manage outside of AWS. You provide the encryption key as part of your PUT request, and S3 uses it to encrypt the object before writing it to disk, then discards the key from memory. This method gives you full control over the key lifecycle while still leveraging S3's server-side encryption infrastructure.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
SSE-C
Why this is correct
Server-side encryption with customer-provided keys.
Related concept
Read the scenario before looking for a memorised answer.
Client-side encryption
Why it's wrong here
Not a built-in S3 encryption method; done on client side.
SSE-S3
Why this is correct
Server-side encryption with S3-managed keys.
Related concept
Read the scenario before looking for a memorised answer.
SSE-KMS
Why this is correct
Server-side encryption with KMS-managed keys.
Related concept
Read the scenario before looking for a memorised answer.
AWS IAM
Why it's wrong here
IAM is for access control, not encryption.
Common exam traps
The trap here is that candidates may confuse client-side encryption (which happens before data reaches S3) with server-side encryption at rest, or incorrectly assume that IAM provides encryption capabilities when it only controls access permissions.
Detailed technical explanation
Under the hood, SSE-C uses the AES-256 algorithm in Galois/Counter Mode (GCM) to encrypt objects, and S3 computes a hash of the provided key to verify integrity without storing the key itself. A subtle behavior is that you must provide the same encryption key for every operation on the object (GET, PUT, HEAD), and if you lose the key, the data is irrecoverable — this is a key management responsibility that differs from SSE-S3 or SSE-KMS where AWS handles key storage. In real-world scenarios, SSE-C is often chosen for regulatory compliance where organizations must retain exclusive control over encryption keys, such as in financial services or healthcare.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
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FAQ
Design for New Solutions — This question tests Design for New Solutions — Read the scenario before looking for a memorised answer..
The correct answer is: SSE-C — SSE-C (Server-Side Encryption with Customer-Provided Keys) is correct because it allows you to encrypt data at rest in S3 using your own encryption keys, which you manage outside of AWS. You provide the encryption key as part of your PUT request, and S3 uses it to encrypt the object before writing it to disk, then discards the key from memory. This method gives you full control over the key lifecycle while still leveraging S3's server-side encryption infrastructure.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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