You can use iTextSharp to modify the attributes of a PDF file-you can only view, copy, and print it.

 

Using iTextSharp. text;

Using iTextSharp.text.pdf;

 

 

Public void pdfreadonly (string comment name)

{

String pdfFile = cmdname; // "d :\\ sampleile ";

 

// Read the file into the memory and immediately release the file handle to overwrite the original file.

PdfReader reader = new PdfReader (File. ReadAllBytes (pdfFile ));

 

// Obtain the MetaData information of this file

Dictionary <string, string> info = reader. Info;

 

Reader. Close ();

 

// Overwrite the original PDF File

Optional stamper = new PdfStamper (reader, new FileStream (pdfFile, FileMode. Create, FileAccess. Write ));

 

Stamper. MoreInfo = info;

Stamper. SetEncryption (writable writer. STRENGTH40BITS, null, null, writable writer. AllowScreenReaders );

 

Stamper. Close ();

}