- A
Server-Side Encryption with S3-Managed Keys (SSE-S3)
Why wrong: SSE-S3 uses encryption keys managed entirely by AWS. This does not satisfy the requirement that the company generates and stores the keys and that AWS never has access to the plaintext key.
- B
Server-Side Encryption with AWS Key Management Service (SSE-KMS) using a customer managed key
Why wrong: Even with a customer managed key, the key is stored and managed within AWS KMS. The compliance policy states that AWS must never have access to the plaintext encryption key, which is not the case with KMS.
- C
Server-Side Encryption with Customer-Provided Keys (SSE-C)
SSE-C allows you to provide your own encryption key with each request to S3. S3 uses the key to encrypt data but does not store the key. This meets the requirement that the company manages the key on-premises and AWS never has access to the plaintext key.
- D
Client-side encryption using the AWS Encryption SDK
Why wrong: Client-side encryption occurs before data is sent to S3; it is not a server-side encryption option offered by S3. While it meets the key control requirement, the question specifically asks for an Amazon S3 encryption option, and client-side encryption is performed by the client application, not S3.
Quick Answer
The answer is Server-Side Encryption with Customer-Provided Keys (SSE-C). This option is correct because it allows you to encrypt S3 data with your own key from an on-premises HSM, while ensuring AWS never has access to the plaintext encryption key. When you upload an object using SSE-C, you provide the encryption key in the request headers; Amazon S3 uses that key to encrypt the data at rest, holds it temporarily in memory only during the encryption or decryption process, and then immediately discards it—never storing the key on AWS infrastructure. On the AWS Certified Cloud Practitioner CLF-C02 exam, this question tests your understanding of the three S3 server-side encryption options and their key management differences. A common trap is confusing SSE-C with SSE-KMS, where AWS manages the key, or SSE-S3, where AWS both manages and stores the key. Remember the memory tip: “C” in SSE-C stands for “Customer controls the key—you bring it, S3 borrows it, then forgets it.”
CLF-C02 Security and Compliance Practice Question
This CLF-C02 practice question tests your understanding of security and compliance. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 must store sensitive financial records in Amazon S3. The compliance policy mandates that the encryption key for data at rest must be generated and stored on the company's own on-premises hardware security module (HSM). The company must never allow AWS to have access to the plaintext encryption key. Which Amazon S3 encryption option should the company use?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"never"Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
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 Customer-Provided Keys (SSE-C)
SSE-C allows the customer to provide their own encryption key, which is used by S3 to encrypt data at rest. AWS temporarily stores the key in memory during the encryption/decryption process but immediately discards it after use, and the key is never stored persistently on AWS infrastructure. This satisfies the compliance requirement that the key must be generated and stored on the company's own on-premises HSM, and AWS never has access to the plaintext key.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 it's wrong here
SSE-S3 uses encryption keys managed entirely by AWS. This does not satisfy the requirement that the company generates and stores the keys and that AWS never has access to the plaintext key.
- ✗
Server-Side Encryption with AWS Key Management Service (SSE-KMS) using a customer managed key
Why it's wrong here
Even with a customer managed key, the key is stored and managed within AWS KMS. The compliance policy states that AWS must never have access to the plaintext encryption key, which is not the case with KMS.
- ✓
Server-Side Encryption with Customer-Provided Keys (SSE-C)
Why this is correct
SSE-C allows you to provide your own encryption key with each request to S3. S3 uses the key to encrypt data but does not store the key. This meets the requirement that the company manages the key on-premises and AWS never has access to the plaintext key.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Client-side encryption using the AWS Encryption SDK
Why it's wrong here
Client-side encryption occurs before data is sent to S3; it is not a server-side encryption option offered by S3. While it meets the key control requirement, the question specifically asks for an Amazon S3 encryption option, and client-side encryption is performed by the client application, not S3.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse SSE-KMS with customer managed keys as meeting the 'customer-controlled key' requirement, but they overlook the fact that AWS KMS still stores the key material and has access to it for decryption operations, which fails the 'never allow AWS to have access to the plaintext encryption key' condition.
Detailed technical explanation
How to think about this question
With SSE-C, the customer provides the encryption key as part of the PUT request header (e.g., x-amz-server-side-encryption-customer-key), and S3 uses AES-256 to encrypt the object. The key is held in volatile memory only for the duration of the request and is never written to disk or logged; this is enforced by the S3 service's internal architecture. In a real-world scenario, a financial institution might use an on-premises HSM to generate and store keys, then securely pass the key to an application that sends it to S3 via the AWS SDK, ensuring the key never resides in AWS storage.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Security and Compliance — study guide chapter
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FAQ
Questions learners often ask
What does this CLF-C02 question test?
Security and Compliance — This question tests Security and Compliance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Server-Side Encryption with Customer-Provided Keys (SSE-C) — SSE-C allows the customer to provide their own encryption key, which is used by S3 to encrypt data at rest. AWS temporarily stores the key in memory during the encryption/decryption process but immediately discards it after use, and the key is never stored persistently on AWS infrastructure. This satisfies the compliance requirement that the key must be generated and stored on the company's own on-premises HSM, and AWS never has access to the plaintext key.
What should I do if I get this CLF-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This CLF-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 CLF-C02 exam.
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