The correct approach is to encrypt the file with a symmetric key, then encrypt that key with each authorized user's public key. This is hybrid encryption, which combines the speed of symmetric cryptography for bulk data with the key management advantages of asymmetric cryptography. The file is encrypted once with a random session key for efficiency, and that session key is then independently encrypted under each user’s public key, allowing multiple users to decrypt the session key with their own private key and access the file without ever sharing a single symmetric key. On the Systems Security Certified Practitioner SSCP exam, this scenario tests your understanding of how to balance performance and access control in shared environments—a common trap is choosing a pure asymmetric solution, which is too slow for large files, or a shared symmetric key, which violates the “no single key” requirement. Memory tip: think “wrap once, unwrap many”—the symmetric key is the wrapper around the file, and each user’s public key wraps that wrapper individually.
SSCP Cryptography Practice Question
This SSCP practice question tests your understanding of cryptography. 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 system administrator is configuring a file encryption solution for a shared network drive. The solution must allow multiple users to read the files without sharing a single symmetric key. Which approach should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Encrypt the file with a symmetric key, then encrypt that key with each authorized user's public key
Option C describes hybrid encryption, which is the correct approach for this scenario. The file is encrypted with a random symmetric key (session key) for efficiency, and that symmetric key is then encrypted with each authorized user's public key. This allows multiple users to decrypt the symmetric key with their private key and then decrypt the file, without sharing a single symmetric 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.
✗
Use a different symmetric key for each user and re-encrypt the file for each user
Why it's wrong here
This is inefficient and requires storing multiple encrypted copies.
✗
Encrypt the file with each user's public key directly
Why it's wrong here
Asymmetric encryption is too slow for large files.
✓
Encrypt the file with a symmetric key, then encrypt that key with each authorized user's public key
Why this is correct
This is a hybrid encryption approach that scales well and maintains security.
Related concept
Read the scenario before looking for a memorised answer.
✗
Encrypt the file with a single symmetric key and share that key securely with all users
Why it's wrong here
Sharing a symmetric key among many users increases risk and management complexity.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may choose Option B (direct public key encryption) because they understand asymmetric encryption but overlook the performance and practical limitations of encrypting large files with public key algorithms, which are designed for small data like keys.
Detailed technical explanation
How to think about this question
Hybrid encryption combines the speed of symmetric encryption (e.g., AES-256) with the key management benefits of asymmetric encryption (e.g., RSA or ECC). In practice, the file is encrypted with a random symmetric key, and that key is encrypted with each user's public key using an algorithm like RSA-OAEP. This is the basis for standards like PGP and S/MIME, and it ensures that only authorized users with the corresponding private key can access the symmetric key and thus the file.
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 developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
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.
Cryptography — This question tests Cryptography — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Encrypt the file with a symmetric key, then encrypt that key with each authorized user's public key — Option C describes hybrid encryption, which is the correct approach for this scenario. The file is encrypted with a random symmetric key (session key) for efficiency, and that symmetric key is then encrypted with each authorized user's public key. This allows multiple users to decrypt the symmetric key with their private key and then decrypt the file, without sharing a single symmetric key.
What should I do if I get this SSCP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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