The answer is non-repudiation, achieved through digital signatures. This is correct because non-repudiation provides cryptographic proof that a specific user sent an email, preventing them from later denying the action. Digital signatures use asymmetric cryptography—such as RSA or ECDSA—combined with a hash of the message to bind the sender’s identity to the content, ensuring both authenticity and integrity. On the Microsoft SC-900 exam, this concept often appears in scenarios about email security and compliance controls, testing your ability to distinguish non-repudiation from related concepts like authentication or encryption. A common trap is confusing digital signatures with encryption: encryption protects confidentiality, while digital signatures provide proof of origin. Remember the mnemonic “Sign to Swear”—a digital signature is like a sworn oath that cannot be denied.
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 security manager wants to ensure that an employee who sends an email cannot later deny having sent it. Which security concept and associated technology is best suited to achieve this?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Non-repudiation, achieved through digital signatures
Non-repudiation ensures that a party cannot deny an action, such as sending an email. Digital signatures, which use asymmetric cryptography (e.g., RSA or ECDSA) and a hash of the message, provide cryptographic proof of the sender's identity and message integrity, making denial impossible.
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.
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Confidentiality, achieved through encryption
Why it's wrong here
Encryption protects data from unauthorized access but does not prove who sent the data; it addresses confidentiality.
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Integrity, achieved through hashing
Why it's wrong here
Hashing ensures data has not been altered but does not link the signature uniquely to the sender, so it does not prevent denial of sending.
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Non-repudiation, achieved through digital signatures
Why this is correct
Digital signatures provide authentication and integrity, and the sender cannot repudiate the signed data because only they possess their private key.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
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Access control, achieved through permissions
Why it's wrong here
Access control determines who can read or write data but does not provide a mechanism to prove that a specific action occurred.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse integrity (hashing) with non-repudiation, not realizing that a hash alone lacks sender identity binding—only a digital signature provides the cryptographic proof of origin needed to prevent denial.
Detailed technical explanation
How to think about this question
Digital signatures work by the sender hashing the message (e.g., with SHA-256) and encrypting that hash with their private key. The recipient decrypts the hash with the sender's public key and recomputes the hash; a match proves the sender's identity and message integrity. In email, S/MIME (RFC 5751) or PGP (RFC 4880) implement this, and the signature is bound to the sender's certificate, which is issued by a trusted Certificate Authority (CA).
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, achieved through digital signatures — Non-repudiation ensures that a party cannot deny an action, such as sending an email. Digital signatures, which use asymmetric cryptography (e.g., RSA or ECDSA) and a hash of the message, provide cryptographic proof of the sender's identity and message integrity, making denial impossible.
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.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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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