[a] technique used to ensure that someone performing an action on a computer cannot falsely deny that they performed that action. Nonrepudiation provides undeniable proof that a user took a specific action, such as transferring money, authorizing a purchase, or sending a message.
Non-repudiation provides protection against an individual falsely denying having performed a particular action. It provides the capability to determine whether a given individual took a particular action such as creating information, sending a message, approving information, and receiving a message. For example, non-repudiation protects individuals against later claims by an author of not having authored a particular document, a sender of not having transmitted a message, a receiver of not having received a message, or a signatory of not having signed a document.