SC-900 Practice Question: Describe the concepts of security, compliance, and identity
A financial institution uses digital signatures to sign all transaction records. This ensures that the records have not been altered after signing. Which security goal does this primarily protect?
⚠ Common exam trap
Test-takers frequently confuse the secondary property of non-repudiation with the primary property of integrity, because digital signatures provide both, but the question's wording 'have not been altered after signing' directly points to integrity, not the ability to prove the signer's identity.
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
✓
Integrity
Digital signatures use asymmetric cryptography (e.g., RSA or ECDSA) to create a hash of the transaction record, which is then encrypted with the signer's private key. Any alteration to the record after signing would cause the hash verification to fail, directly protecting the integrity of the data. While digital signatures also support non-repudiation, the question specifically asks which goal is primarily protected by ensuring records have not been altered, which is integrity.
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
Why it's wrong here
Confidentiality, a core security principle, focuses on preventing unauthorized disclosure of information, ensuring that data is accessible only to those with appropriate permissions. Digital signatures, however, do not encrypt the content of a document; instead, they verify its origin and detect alterations. Therefore, while vital for overall security, digital signatures do not directly provide or enhance the confidentiality of the financial institution's records.
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Non-repudiation
Why it's wrong here
Non-repudiation, a distinct security service provided by digital signatures, ensures that a signer cannot legitimately deny having signed a document, and a recipient cannot deny having received it. This is achieved by cryptographically linking the signature to the signer's unique private key. While digital signatures offer non-repudiation, the question specifically asks about ensuring records have not been *altered*, which directly pertains to data integrity rather than preventing the denial of an action.
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Integrity
Why this is correct
Integrity ensures that data remains accurate, complete, and has not been modified or tampered with by unauthorized parties. Digital signatures achieve this by generating a unique cryptographic hash of the document's content, which is then encrypted with the signer's private key. Any subsequent alteration to the document, even a single character, will cause a mismatch between the recomputed hash and the decrypted hash from the signature, thereby immediately indicating that the record's integrity has been compromised.
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Availability
Why it's wrong here
Availability, another fundamental security principle, guarantees that authorized users can access information and systems when needed, without undue delay or interruption. This is typically maintained through robust infrastructure, redundancy, backups, and disaster recovery planning. Digital signatures, conversely, are designed to verify the authenticity and integrity of data, and do not directly contribute to the accessibility or uptime of systems or information.
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 |
Go deeper
Related to this question
Learn chapter
Core Security Concepts
Key term
Integrity
Integrity is the assurance that data has not been altered or tampered with in an unauthorized way, preserving its accuracy and consistency from source to destination.
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SC-900 practice question is part of Courseiva's free Microsoft 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 SC-900 exam.