Nonrepudiation in Information Assurance refers to which concept?

• A. The origin of information cannot later deny having sent it; the recipient can verify authenticity.
• B. Data can be deleted without trace.
• C. Users can deny login attempts.
• D. The system can operate without authentication.

Answer: (A)

Nonrepudiation means that once a message or action is performed, the origin cannot be denied later, and others can verify who sent it and that it wasn’t altered. In information assurance this is achieved with mechanisms like digital signatures and auditable logs. A sender signs content with a private key, and the recipient—or any verifier—uses the sender’s public key to confirm the signature and thus the origin, while timestamps and logs provide evidence for accountability. This combination prevents someone from later denying that they sent or signed the data, which is crucial for audits and nonrepudiation agreements. The other ideas don’t fit because deleting data without trace doesn’t prove who sent it; denying login attempts relates to authentication rather than proving actions, and operating without authentication removes the ability to attribute actions to a user, undermining nonrepudiation.