InterComponentWare AG Fraunhofer Gesellschaft Cygnacom Solutions There are many scenarios in which users must be able to prove the existence of data at a specific point in time and be able to demonstrate the integrity of data since that time, even when the duration from time of existence to time of demonstration spans a large period of time. Additionally, users must be able to verify signatures on digitally signed data many years after the generation of the signature. This document describes a class of long-term archive services to support such scenarios and the technical requirements for interacting with such services. This memo provides information for the Internet community.