Tnx for your comment.
As far as your solution:
first, I have never wrote "How do I safely store encryption keys for my application?".
The original subject is and was always the same!
I have closed the previous question and reworded Alex.P with 500 points (Tnx Alex.P).
Due to your solution I have decided to open a new question (as a follow up) and specifically wrote that the solution must be for deploying the application on multiple client PCs. I need a solution to all casses - encryption on a web server (WebForm) and on multiple client PCs (WinForm).
secone, as far as I know the APAPI is good for working on a single computer (web server) without having to deploy your application to multiple clients using WinForms !!!
Or maybe i should say that the encryption key generated using the DPAPI is special to the machine that the application is running on.
by that NO-ONE cane decrypt a key that is generated and stored on a registry of another machine, but surly you can decryp a key that is generated and stored on your client machine (WinForm).
please let me know if I am right or maybe I got it all wrong ?!?!