To demonstrate the ease of using the SEM architecture we implemented a plug-in for the Eudora email reader [15]. When sending signed email the plug-in reads the user bundle described in the previous section. It obtains the SEM address from the bundle and then communicates with the SEM to sign the email. The resulting signed email can be verified using any S/MIME capable email client such as Microsoft Outlook. In other words, the email recipient is oblivious to the fact that a SEM is used to control the sender's signing capabilities.
Figure 2 shows a screen snap shot of trying to send signed email using a revoked key. In this example, the plug-in contacts the SEM and is told that the SEM will not supply the token for a revoked key. Consequently, the plug-in displays a message informing the user that the email cannot be signed.
