Hi, there is a demand in my project,we know that we can encrypt a pdf file,set the permissions that whether the users can copy/print from pdf-files,

now we want to set a timespan of these permissions, for example: before Dec 31, 2010,the pdf file need a password to access and can not be copy/printed, after this period,user can open the file without limits (need to remove the limits we set before).

Is there any solution of this issue? [I use iTextSharp.dll to create \encrypt PDF file in .NET(C#)]