The goal of the non-repudiation service is to generate, collect, maintain, make available and validate evidence concerning a claimed event or action in order to resolve disputes about the occurrence or non-occurrence of the event or action. This part of ISO/IEC 13888 provides descriptions of generic structures that can be used for non-repudiation services, and of some specific communication-related mechanisms which can be used to provide non-repudiation of origin (NRO) and non-repudiation of delivery (NRD). Other non-repudiation services can be built using the generic structures described in this part of ISO/IEC 13888 in order to meet the requirements defin