SSCP Cryptography Practice Question
An organization is implementing a digital signature solution to ensure non-repudiation of documents. Which combination of keys is used during the signing process?
⚠ Common exam trap
ISC2 SSCP often tests the misconception that signing uses a public key or that verification uses a private key, leading candidates to confuse the roles of keys in encryption versus signing.
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
✓
Sender's private key to sign, sender's public key to verify
Digital signatures use asymmetric cryptography where the sender creates a signature with their private key, and the recipient verifies it with the sender's public key. This ensures non-repudiation because only the sender possesses their private key, so they cannot deny having signed the document. The process typically involves hashing the document and encrypting the hash with the sender's private key.
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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Recipient's public key to sign, recipient's private key to verify
Why it's wrong here
This describes encryption for confidentiality, not digital signatures.
- ✓
Sender's private key to sign, sender's public key to verify
Why this is correct
The private key creates the signature, and the corresponding public key verifies it.
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Sender's public key to sign, recipient's private key to verify
Why it's wrong here
Signing uses the private key, not the public key.
- ✗
A shared symmetric key for both signing and verification
Why it's wrong here
Symmetric keys do not provide non-repudiation.
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.