Long-term security for signed documents: Services, protocols, and data structures

Long-term retention of electronically signed documents brings with certain problems: Signed documents may loose their probative value over the years and changing of data formats breaks the original signature. In this paper, we analyze the state of the art to resolve these problems and describe requirements, existing and partially field-tested concepts, data structures and specifications of service protocols. Solutions for the aging problem are already in an advanced state, whereas in the area of secure transformation merely first requirements and solution concepts may be presented. Since many organizations, and, in particular, SMEs and individuals are confronted by the challenge how to technically and organizationally implement existing concepts we describe services caring about the long-terns and law-abiding preservation of electronic documents. In this way users of a web service are not forced to deal with the complex process of securing their documents over long periods of time.