ISC Systems Security Engineering Foundations Practice Question
When designing a system for 'Non-repudiation', which technical control is essential?
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
✓
Digital signatures
Digital signatures using public-key cryptography ensure that a message or transaction can be linked to a specific user and not disavowed.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Digital signatures
Why this is correct
Signatures provide cryptographic proof of origin.
- ✗
Basic username/password authentication
Why it's wrong here
Passwords can be shared and do not prove intent.
- ✗
Hashing only
Why it's wrong here
Hashing alone does not link a user to an action.
- ✗
Symmetric encryption
Why it's wrong here
Symmetric keys are shared and do not provide non-repudiation.
Quick reference
Asymmetric Encryption Algorithm Comparison
| Algorithm | Key Exchange | Signatures | Equivalent Security Key | Notes |
|---|---|---|---|---|
| RSA-3072 | Yes | Yes | 128-bit | Widely deployed; slow for bulk data |
| ECDSA P-256 | No | Yes | 128-bit | Fast signatures; standard TLS certs |
| ECDH / ECDHE | Yes | No | 128-bit | Perfect forward secrecy in TLS 1.3 |
| DH / DHE | Yes | No | 128-bit (3072-bit key) | Replaced by ECDHE in modern TLS |
| Ed25519 | No | Yes | ~128-bit | SSH keys, modern PKI |
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official (ISC)² exam blueprint
This ISC practice question is part of Courseiva's free (ISC)² 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 ISC exam.