Which of the following terms refers to a mechanism which proves that the sender really sent a particular message?

Confidentiality ensures data is accessible only to authorized parties through encryption, but it does not prove the identity of the message sender.

Authentication verifies the identity of a user or system at a point in time but does not create binding cryptographic proof that a specific message was sent by that party.

Non-repudiation uses mechanisms such as digital signatures to cryptographically bind a message to its originator, creating irrefutable and verifiable evidence of who sent it. This is distinct from authentication because it produces persistent, legally defensible proof that a specific party originated a specific message. It is a core security service defined in frameworks such as NIST SP 800-57 for this exact purpose.

Integrity ensures that data has not been altered or tampered with in transit, but it does not identify or prove who originated the message.