Encrypt PDF Document and Set Permissions – C#/VB.NET

Sometimes, we may find that our documents which are submitted to internet are edited by others, even someone steal it and write his/her name as author in documents. It lets us depressed. Therefore, it is necessary to protect our documents. In this post, I will introduce one method to encrypt PDF by C#/VB.NET.

How to protect document? The frequently used method is to encrypt it. Owner gives a password for document. People, including owner must use correct password to open document. Also, owner can set permissions for document, for example, allowing to printing.

In my example, I prepare a PDF document. I want to encrypt it and the password for me and others are different. After opening it, I will set other two permissions, allowed to printing and filling fields.

Then, let’s go to steps. Because I use Spire.PDF in this method, so I add its dll file as reference at the beginning.

  1. Load PDF document from my computer.
  2. Encrypt PDF. Firstly, set password length. Secondly, set owners password and others password. Thirdly, set permissions.
  3. Save and launch new document.

Main Coding:


using System;

using Spire.Pdf;

using Spire.Pdf.Security;

namespace EncryptPDF


    class Encryption


        static void Main(string[] args)


            //Load File

            PdfDocument doc = new PdfDocument();

            doc.LoadFromFile(@”D:\work\My Documents\Shelley.pdf”);


            doc.Security.KeySize = PdfEncryptionKeySize.Key128Bit;

            doc.Security.OwnerPassword = “123456”;

            doc.Security.UserPassword = “654321”;

            doc.Security.Permissions = PdfPermissionsFlags.Print | PdfPermissionsFlags.FillFields;

            //Save and Launch File








Imports System

Imports Spire.Pdf

Imports Spire.Pdf.Security

Namespace EncryptPDF

       Friend Class Encryption

              Shared Sub Main(ByVal args() As String)

                     ‘Load File

                     Dim doc As New PdfDocument()

                     doc.LoadFromFile(“D:\work\My Documents\Shelley.pdf”)


                     doc.Security.KeySize = PdfEncryptionKeySize.Key128Bit

                     doc.Security.OwnerPassword = “123456”

                     doc.Security.UserPassword = “654321”

                     doc.Security.Permissions = PdfPermissionsFlags.Print Or PdfPermissionsFlags.FillFields

                     ‘Save and Launch File




              End Sub

       End Class

End Namespace

Result Shown by Following:


Click Here to Learn more about Spire.PDF

Click Here to Download Spire.PDF


2 thoughts on “Encrypt PDF Document and Set Permissions – C#/VB.NET

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