SC-900 Practice Question: Describe the concepts of security, compliance, and identity
This SC-900 practice question tests your understanding of describe the concepts of security, compliance, and identity. 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 company uses digital signatures to ensure that a sender cannot later deny having sent a message. Which security principle does this primarily address?
Why wrong: Confidentiality is achieved through encryption, not digital signatures. Digital signatures do not hide the content; they provide authenticity and non-repudiation.
B
Integrity
Why wrong: While digital signatures also provide integrity (detecting tampering), the primary focus of the scenario is preventing denial of sending, which is non-repudiation.
C
Availability
Why wrong: Availability deals with ensuring resources are accessible; digital signatures do not impact availability.
D
Non-repudiation
Non-repudiation specifically addresses the inability to deny an action. Digital signatures provide cryptographic proof of origin and consent, ensuring the sender cannot deny sending the message.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Non-repudiation
Digital signatures use asymmetric cryptography (e.g., RSA or ECDSA) to bind a signer's identity to a message. The signature is created with the sender's private key and verified with their public key, providing cryptographic proof of origin. This directly enforces non-repudiation because the sender cannot plausibly deny having signed the message, as only they possess the private key.
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.
✗
Confidentiality
Why it's wrong here
Confidentiality is achieved through encryption, not digital signatures. Digital signatures do not hide the content; they provide authenticity and non-repudiation.
✗
Integrity
Why it's wrong here
While digital signatures also provide integrity (detecting tampering), the primary focus of the scenario is preventing denial of sending, which is non-repudiation.
✗
Availability
Why it's wrong here
Availability deals with ensuring resources are accessible; digital signatures do not impact availability.
✓
Non-repudiation
Why this is correct
Non-repudiation specifically addresses the inability to deny an action. Digital signatures provide cryptographic proof of origin and consent, ensuring the sender cannot deny sending the message.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse digital signatures with encryption, assuming they primarily provide confidentiality, when in fact signatures focus on authentication and non-repudiation, while encryption (e.g., using the recipient's public key) is what ensures confidentiality.
Trap categories for this question
Scenario analysis trap
While digital signatures also provide integrity (detecting tampering), the primary focus of the scenario is preventing denial of sending, which is non-repudiation.
Detailed technical explanation
How to think about this question
Under the hood, a digital signature is computed by hashing the message (e.g., with SHA-256) and then encrypting that hash with the sender's private key. The recipient decrypts the hash with the sender's public key and compares it to a freshly computed hash of the message; if they match, both integrity and non-repudiation are confirmed. In real-world PKI, a Certificate Authority (CA) issues the sender's certificate, binding the public key to the sender's identity, which is critical for legal non-repudiation in scenarios like signed email (S/MIME) or code signing.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-900 question in full detail.
Describe the concepts of security, compliance, and identity — This question tests Describe the concepts of security, compliance, and identity — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Non-repudiation — Digital signatures use asymmetric cryptography (e.g., RSA or ECDSA) to bind a signer's identity to a message. The signature is created with the sender's private key and verified with their public key, providing cryptographic proof of origin. This directly enforces non-repudiation because the sender cannot plausibly deny having signed the message, as only they possess the private key.
What should I do if I get this SC-900 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.
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Question Discussion
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