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SSCP Practice Question: Which TWO factors are most critical when…
Which TWO factors are most critical when selecting a cryptographic algorithm for a government application?
⚠ Common exam trap
ISC2 often tests the misconception that speed or popularity are primary selection criteria, when in fact government applications are driven by regulatory mandates and cryptographic strength (key length) as defined by standards like FIPS.
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
✓
Key length
For a government application, regulatory compliance (D) is critical because government systems must use algorithms and modules validated under standards such as FIPS 140-2 (or its successor FIPS 140-3), and non-compliant cryptography cannot legally be deployed in many federal environments. Key length (B) is equally critical because it directly determines the cryptographic strength and resistance to brute-force or cryptanalytic attacks, and government standards mandate minimum key sizes (e.g., AES-128/192/256, RSA or Diffie-Hellman of at least 2048 bits, ECC of at least 224 bits). Speed of encryption/decryption (A) is a performance consideration, not a primary selection factor for government cryptographic approval. Algorithm popularity (C) is irrelevant to security assurance and can even be misleading, as popularity does not imply validation. Ease of implementation (E) affects development effort but does not determine whether an algorithm meets government security and compliance requirements.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Speed of encryption/decryption
Why it's wrong here
Government selection prioritises algorithm strength and FIPS 140-2/140-3 validation, not throughput; speed is a performance consideration for high-volume commercial workloads. A fast but unapproved algorithm cannot be deployed in classified systems, so speed alone fails the approval requirement.
- ✓
Key length
Why this is correct
Key length determines the brute-force resistance of the algorithm; longer keys increase the work factor for attackers. For government use, sufficient key length is critical to withstand sustained cryptanalysis, though it must be paired with an approved algorithm and mode.
- ✗
Algorithm popularity
Why it's wrong here
Popularity reflects adoption, not cryptographic strength or standardisation. Government schemes require algorithms approved under FIPS 140-2/140-3 and NIST SP 800-131A; a widely used but unvalidated algorithm cannot be authorised. Popularity would matter only for interoperability with existing commercial deployments.
- ✓
Regulatory compliance (e.g., FIPS 140-2)
Why this is correct
Regulatory compliance such as FIPS 140-2 mandates validated cryptographic modules and approved algorithms for government systems. Selecting a non-compliant algorithm, however strong, would fail certification requirements, making compliance a critical selection factor alongside key length.
- ✗
Ease of implementation
Why it's wrong here
Ease of implementation is an operational convenience, not a security criterion; government selection prioritises algorithm strength and approved standards such as FIPS 140 validation and suite guidance. Implementation effort matters for delivery schedules, which is why it is tempting, but it cannot outweigh cryptographic strength, key length and compliance mandates.
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 |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.