Which security principle requires that a system have a high degree of confidence about the identity of the actor performing an action?

• A. Authentication
• B. Non-repudiation
• C. Confidentiality
• D. Availability

Answer: (B)

The main concept here is authentication: verifying who is performing an action. It’s about establishing confidence that the current user or actor is who they claim to be, so the system can grant the right permissions and attribute actions to the correct identity. This is typically done through credentials like passwords, tokens, biometrics, or digital certificates, often using multiple factors to strengthen trust.

Non-repudiation, while related, deals with ensuring that a party cannot deny having performed an action after it’s occurred, usually through irreversible evidence like digital signatures and secure audit logs. Confidentiality and availability address different goals—keeping data secret and ensuring access to services, not directly about proving identity at the moment of action.