220-1102 Security Practice Question
A company's security policy requires that all data stored in the cloud be encrypted before upload to ensure the cloud provider cannot read it. Which encryption method satisfies this requirement?
⚠ Common exam trap
Test-takers frequently confuse encryption at rest or in transit with client-side encryption, assuming that any encryption method prevents the provider from reading the data, but they overlook who controls the encryption keys.
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
Client-side encryption ensures data is encrypted by the client before it is uploaded to the cloud provider. This means the cloud provider never has access to the unencrypted data or the encryption keys, satisfying the requirement that the provider cannot read the data. The encryption occurs on the client's system using tools like AES-256, and only the ciphertext is transmitted to the cloud.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Encryption in transit only
Why it's wrong here
Encryption in transit only protects data while it is being transmitted over the network, typically through TLS/HTTPS. Once the data reaches the cloud provider's storage, it is either stored in plaintext or protected only by whatever default encryption the provider applies, leaving the provider with access to the raw data. Because the policy requires all stored data to be encrypted and unreadable by the provider, this measure fails to address the at-rest component of the requirement.
- ✗
Encryption at rest managed by the provider
Why it's wrong here
Encryption at rest managed by the provider means the cloud provider encrypts data once it is written to disk, but the provider also controls the encryption keys through its key management service. Since the provider holds the keys, it has the ability to decrypt the data at any time, for example during routine maintenance or if legally compelled. This approach stops external attackers from reading the data, but it does not prevent the provider itself from accessing it, so it violates a policy requiring the provider to be unable to read the data.
- ✓
Client-side encryption
Why this is correct
Client-side encryption encrypts the data on the client's device before it is uploaded to the cloud, using cryptographic keys that the provider never receives. The cloud service stores only ciphertext, so even if the provider gains full access to its infrastructure, it cannot decrypt the data without the client-held keys. This creates a zero-knowledge or end-to-end encryption model that satisfies a security policy demanding that stored data be unreadable by the provider.
- ✗
Server-side encryption managed by the provider
Why it's wrong here
Server-side encryption managed by the provider is applied after the data is uploaded, when the server writes it to encrypted storage, with the provider's key management service managing the master keys. This ensures that files are encrypted at rest, but the provider retains the decryption keys and therefore can read the plaintext whenever it chooses to do so, for example to support server-side processing or access requests. The provider's ability to decrypt data means this option does not meet a requirement that the provider itself must not be able to read the stored information.
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 |
Go deeper
Related to this question
Learn chapter
Encryption Concepts for A+
Key term
Advanced Encryption Standard
Advanced Encryption Standard (AES) is a widely used symmetric encryption algorithm that protects electronic data by converting readable information into a scrambled format that can only be unscrambled with the correct secret key.
Key term
Security policy
A security policy is a formal set of rules and guidelines that an organization establishes to protect its information assets and technology resources.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1102 practice question is part of Courseiva's free CompTIA 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 220-1102 exam.