Protection of Signed Documents Against Unauthorized Modification

Objective 

 Once a document is signed or certified, protect it so that any later change can be detected. 

 Guidelines 

 After a document has been digitally signed or certified: 

 

 Any change to the document must cause the signature validation to fail or clearly show that the document was modified. 

 Your system must be able to detect unauthorized changes made after signing. 

 No one should be able to add, remove, or change content without that change being detectable. 

 It must be possible to verify the document's integrity at any time — today, next month, or years from now.