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Difficulty: MediumCIA Triad and Non-Repudiation

A healthcare provider is deploying a tele-radiology platform where remote radiologists submit diagnostic reports to hospital electronic health record (EHR) systems. Security policy dictates that the platform must guarantee two key objectives: (1) hospitals must be able to prove which specific radiologist authored a report such that the radiologist cannot later claim they did not send it, and (2) any alteration to report contents during transit or storage must be immediately detectable. Which of the following technical controls must be implemented to fulfill these security requirements? (Select TWO.)

  1. Digital signatures applied to diagnostic reports using each radiologist's private keyAnswer
  2. Cryptographic hashing generated for report payloads prior to transmissionAnswer
  3. C
    Symmetric encryption of reports using a shared AES-256 secret key among all hospitals
  4. D
    Role-based access control (RBAC) enforced on the central EHR portal

Answer

The organization must implement digital signatures applied with individual private keys (to provide non-repudiation and integrity) and cryptographic hashing of report payloads (to verify data integrity).
Digital signatures created with asymmetric private keys provide non-repudiation by binding the specific sender's identity to the report, while cryptographic hashing generates verification digests that detect any file alterations to preserve integrity.

Step-by-Step Solution

1
Analyze Requirement 1: Non-repudiation of authorship
Non-repudiation requires a mechanism where the sender's identity is cryptographically bound to the data using a secret known only to the sender (a private key). Digital signatures fulfill non-repudiation because only the private key owner could have produced the signature.
Symmetric shared keys or standard login permissions cannot prove individual authorship since keys/credentials may be shared or managed centrally.
2
Analyze Requirement 2: Detection of unauthorized modifications (Integrity)
Data integrity is verified using cryptographic hash functions (such as SHA-256) or digital signatures. Comparing the computed hash digest against the expected hash reveals any tampering in transit or storage.
Hashing creates a deterministic value unique to the exact byte sequence of the diagnostic file.
3
Evaluate distractors against CIA and Non-Repudiation concepts
Symmetric encryption with a shared key ensures confidentiality but fails non-repudiation. RBAC enforces authorization permissions but cannot cryptographically prove data integrity or origin.
Confidentiality and authorization address different security pillars than non-repudiation and integrity.

Key Concept

CIA Triad and Non-Repudiation
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Topics

CIA Triad and Non-Repudiation

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