Prevention of Additional Untrusted Signatures

Objective 

 Stop anyone from quietly adding an unauthorized or untrusted signature to a document that was already signed by the system. 

 Guidelines 

 A document signed through the PKI system must be protected so that extra, untrusted signatures cannot be added without detection. 

 Example: Someone should not be able to take a document signed by your system, add their own signature using an untrusted certificate, and have it appear legitimate.