This section describes the implementation of the offline delegation mechanism in greater detail. The implementation of the File Repository currently runs on Unix and Windows NT. As PDA we have used the Palm-III from 3Com with PalmOS as the operating system. The offline delegation mechanism is hosted both on the PDA and on Unix workstations.
In addition to FR itself, the implementation consists of a library with cryptographic functions, a library to parse and generate SDSI objects and a graphical user interface to create/send and receive/verify certificates on the PDA. First we will describe the user interface of the offline-delegation application running on the PDA. It is by means of this application that the users can create, send and receive certificates. Then we will focus on the two libraries that are part of our implementation. The first library contains cryptographic functions to create short digital signatures. The second library converts certificates between internal and external representations.