Develop a tool able to add a Watermark to a .PDF sent to printer (to be printed over the initial text). The .PDF is digitally sign and will not be altered as the signature will be altered. The watermark consists the file name. e.g. the name of the file is [url removed, login to view]
We have developed a desktop app that dowloads the .pdf file, renames it and sends it to printer and we need this tool to do this job (and to be accesed by our app).
It is a very important thing not to alter the .pdf file as the signature has to remain attached to the file.
The tool should be developed in C#, the source code should be delivered in order to be included in our C# app and will not use any third party libraries unless they are free to use.
The print should also include the signature. Printed document + watermark but not having the signature is not acceptable.