SCS-C02 Infrastructure Security Practice Question
A company wants to ensure that all traffic to an Amazon S3 bucket is encrypted in transit. Which bucket policy condition should be used?
⚠ Common exam trap
Test-takers frequently confuse encryption in transit (HTTPS/TLS) with encryption at rest (server-side encryption), leading candidates to incorrectly select `s3:x-amz-server-side-encryption` instead of `aws:SecureTransport`.
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
✓
aws:SecureTransport
The `aws:SecureTransport` condition key checks whether the request was sent using SSL/TLS (i.e., HTTPS). Setting it to `false` in a deny statement ensures that any HTTP request to the S3 bucket is rejected, thereby enforcing encryption in transit. This is the correct condition for the stated requirement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
aws:SourceVpce
Why it's wrong here
The aws:SourceVpce condition key restricts access to requests that originate from a specific VPC endpoint, such as vpce-12345678. It is useful for enforcing that traffic enters via a private network path, but it has no bearing on whether the request is encrypted. A client can still send plaintext HTTP traffic through a VPC endpoint, so this key cannot be used to enforce encryption in transit.
- ✓
aws:SecureTransport
Why this is correct
The aws:SecureTransport condition key is a boolean context key that indicates whether the request was sent over SSL/TLS: it is true for HTTPS and false for plaintext HTTP. In a bucket policy, you can add a Deny statement with a condition like {"Bool":{"aws:SecureTransport":"false"}} to block all unencrypted requests. This directly ensures that every request to the S3 bucket is encrypted during transit.
- ✗
s3:x-amz-server-side-encryption
Why it's wrong here
The s3:x-amz-server-side-encryption condition key evaluates the x-amz-server-side-encryption header sent by the client to request server-side encryption at rest, such as AES256 or aws:kms. It guarantees that the object is stored encrypted on S3's managed infrastructure, but it does not protect the data while it is being transmitted. An attacker on the network could still read plaintext traffic before it reaches S3, because this header does not influence the transport protocol.
- ✗
aws:SourceIp
Why it's wrong here
The aws:SourceIp condition key restricts requests to those originating from a specific IP address or CIDR range, such as an on-premises corporate network. This is a network-layer access control and has no relationship to the encryption of the request payload. Even if a request comes from an allowed source IP, it could still be sent unencrypted over HTTP, so this condition cannot be used to enforce encryption in transit.
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
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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.