- A
Keyed hash (HMAC)
Why wrong: HMAC provides integrity and authentication but not non-repudiation because the key is shared between parties.
- B
Digital signature using RSA or ECDSA
Digital signatures bind the identity of the signer to the data, providing non-repudiation.
- C
Hash function only
Why wrong: Hashing alone does not provide authentication; an attacker can modify both message and hash.
- D
Symmetric encryption with a shared key
Why wrong: Symmetric encryption cannot prove origin because both parties share the key.
Question 958 of 1,000
SSCP Cryptography Practice Question
This SSCP practice question tests your understanding of cryptography. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 security engineer is designing a system that requires non-repudiation of data origin. Which cryptographic technique should be used?
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 signature using RSA or ECDSA
Digital signatures using RSA or ECDSA provide non-repudiation of data origin because they bind the signer's identity to the data through a private key that only the signer possesses. The recipient can verify the signature with the corresponding public key, and the signer cannot later deny having signed the data, as the private key is uniquely under their control. This meets the legal and technical requirement for non-repudiation, unlike symmetric or hash-only methods.
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.
- ✗
Keyed hash (HMAC)
Why it's wrong here
HMAC provides integrity and authentication but not non-repudiation because the key is shared between parties.
- ✓
Digital signature using RSA or ECDSA
Why this is correct
Digital signatures bind the identity of the signer to the data, providing non-repudiation.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Hash function only
Why it's wrong here
Hashing alone does not provide authentication; an attacker can modify both message and hash.
- ✗
Symmetric encryption with a shared key
Why it's wrong here
Symmetric encryption cannot prove origin because both parties share the key.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse integrity (provided by HMAC or hash) with non-repudiation, or assume a shared secret (HMAC or symmetric encryption) can prove origin, but only asymmetric digital signatures satisfy the legal requirement of non-repudiation.
Detailed technical explanation
How to think about this question
Non-repudiation relies on asymmetric cryptography where the signing private key is never shared; RSA PKCS#1 v1.5 or PSS and ECDSA (per FIPS 186-5) generate a signature that can be verified by anyone with the public key. In practice, X.509 certificates bind the public key to an identity, and protocols like TLS 1.3 or S/MIME use digital signatures for non-repudiation. A subtle behavior: if the private key is compromised, non-repudiation is lost, which is why hardware security modules (HSMs) are often used to protect signing keys.
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.
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 |
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.
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FAQ
Questions learners often ask
What does this SSCP question test?
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: Digital signature using RSA or ECDSA — Digital signatures using RSA or ECDSA provide non-repudiation of data origin because they bind the signer's identity to the data through a private key that only the signer possesses. The recipient can verify the signature with the corresponding public key, and the signer cannot later deny having signed the data, as the private key is uniquely under their control. This meets the legal and technical requirement for non-repudiation, unlike symmetric or hash-only methods.
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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Last reviewed: Jul 4, 2026
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.
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