Digital signature for autocad image/word document

Question

hi @gnanavel,

    im trying to digitally sign the word document and autocad drawing and images using asp.net core.here im using 

Using .Net X509 Certificates to Sign Images and Documents (C# .Net) | by Suminda Niroshan | The Startup | Medium this ,in this signing process happens by using my own digital certificate but can able to see the sign in the documents.kindly check this link and revert me back.thanks in advance