The correct answer is AES-256 and Blowfish, as both are symmetric block ciphers well-suited for encryption algorithms for data at rest on a file server. AES-256 is the modern gold standard, offering a fixed 256-bit key and robust security through its substitution-permutation network, while Blowfish supports variable key lengths from 32 to 448 bits and was historically favored for fast software-based file and disk encryption. On the Systems Security Certified Practitioner SSCP exam, this question tests your ability to distinguish between symmetric algorithms appropriate for stored data versus those designed for transit or asymmetric purposes; a common trap is selecting RSA or ECC, which are for key exchange and digital signatures, not bulk encryption. Remember that data at rest requires symmetric block ciphers like AES or Blowfish, not stream ciphers or asymmetric ones. A helpful memory tip: "At rest, symmetric is best—AES and Blowfish pass the test."
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 company is implementing encryption for data at rest in a file server. Which TWO of the following algorithms are suitable for this purpose? (Select TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Blowfish
Blowfish is a symmetric block cipher that supports variable key lengths (32–448 bits), making it suitable for encrypting data at rest on a file server. It is designed for fast encryption in software and has been widely used for file and disk encryption, though it is now considered less secure than modern alternatives like AES.
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.
✗
3DES
Why it's wrong here
3DES is deprecated and considered too weak for secure encryption.
✓
Blowfish
Why this is correct
Blowfish is a symmetric block cipher that can be used for data at rest, though AES is preferred.
Related concept
Read the scenario before looking for a memorised answer.
✗
SHA-256
Why it's wrong here
SHA-256 is a cryptographic hash function, not an encryption algorithm.
✓
AES-256
Why this is correct
AES-256 is a standard symmetric encryption algorithm suitable for data at rest.
Related concept
Read the scenario before looking for a memorised answer.
✗
RSA-2048
Why it's wrong here
RSA is an asymmetric algorithm for key exchange and digital signatures, not for data at rest encryption.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse hashing algorithms (like SHA-256) with encryption algorithms, or mistakenly think asymmetric ciphers (like RSA) are suitable for bulk data encryption, when in fact symmetric ciphers (like AES and Blowfish) are the correct choice for data at rest.
Detailed technical explanation
How to think about this question
Blowfish uses a Feistel network with 16 rounds and key-dependent S-boxes, which complicates cryptanalysis but also makes it slower to set up keys. In practice, Blowfish has been largely superseded by AES-256, which uses a 128-bit block size and is the NIST-approved standard for encrypting data at rest, offering hardware acceleration (AES-NI) on modern CPUs for high throughput. AES-256 with XTS mode is commonly used for full-disk encryption (e.g., BitLocker, LUKS) because it provides both confidentiality and tweakable encryption to prevent block reordering attacks.
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: Blowfish — Blowfish is a symmetric block cipher that supports variable key lengths (32–448 bits), making it suitable for encrypting data at rest on a file server. It is designed for fast encryption in software and has been widely used for file and disk encryption, though it is now considered less secure than modern alternatives like AES.
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.
About these practice questions
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This SSCP practice question is part of Courseiva's free ISC2 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 SSCP exam.
Question Discussion
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