Which concept provides proof that a specific action occurred or that someone or something is who they claim to be?

• A. Integrity
• B. Confidentiality
• C. Nonrepudiation
• D. Availability

Answer: (C)

Nonrepudiation is the idea that you can prove an action occurred and verify who performed it, so the actor can’t deny involvement later. In practice it’s supported by cryptographic signatures, timestamps, and tamper-evident audit logs that bind a specific entity to a specific event or message. This provides verifiable evidence that a transaction happened and that the claimed identity was involved, which is essential for accountability in health information systems. While integrity, confidentiality, and availability protect other properties—data hasn’t been altered, information is kept secret, and systems remain accessible—they don’t by themselves establish undeniable proof of who did what.