How to ensure a file that an user uploads was initially downloaded from the system

Question

For security purposes we want to ensure the user is uploading a file that was initially downloaded from the system. The file type is excel and application is in.NET CORE.

Solution I am thinking is to add a custom property(say author) to the file. We have the byte array and would like to append a byte array that would add that custom property. Ideally doing the above update before return the file return File(fileData, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", fileName);