PDFsharp Sample: Unprotect Document

Modified on 2015/09/14 10:20 by Thomas Hövel — Categorized as: PDFsharp Samples, Samples

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This sample shows how to unprotect a document (if you know the password).

Note:  that we will not explain nor give any tips how to crack a protected document with PDFsharp.

PDF Output File

See the PDF file created by this sample: output.pdf (7 kB)

Screen Shots

Here is a sample screen shot:

The unprotected document with some added text

Source Code

This code shows how to unprotect a document to allow modification:
// Get a fresh copy of the sample PDF file.
// The passwords are 'user' and 'owner' in this sample.
const string filenameSource = "HelloWorld (protected).pdf";
const string filenameDest = "HelloWorld_tempfile.pdf";
File.Copy(Path.Combine("../../../../../PDFs/", filenameSource),
  Path.Combine(Directory.GetCurrentDirectory(), filenameDest), true);
PdfDocument document;
// Opening a document will fail with an invalid password.
  document = PdfReader.Open(filenameDest, "invalid password");
catch (Exception ex)
// You can specifiy a delegate, which is called if the document needs a
// password. If you want to modify the document, you must provide the
// owner password.
document = PdfReader.Open(filenameDest, PdfDocumentOpenMode.Modify, PasswordProvider);
// Open the document with the user password.
document = PdfReader.Open(filenameDest, "user", PdfDocumentOpenMode.ReadOnly);
// Use the property HasOwnerPermissions to decide whether the used password
// was the user or the owner password. In both cases PDFsharp provides full
// access to the PDF document. It is up to the programmer who uses PDFsharp
// to honor the access rights. PDFsharp doesn't try to protect the document
// because this make little sence for an open source library.
bool hasOwnerAccess = document.SecuritySettings.HasOwnerPermissions;
// Open the document with the owner password.
document = PdfReader.Open(filenameDest, "owner");
hasOwnerAccess = document.SecuritySettings.HasOwnerPermissions;
// A document opened with the owner password is completely unprotected
// and can be modified.
XGraphics gfx = XGraphics.FromPdfPage(document.Pages[0]);
gfx.DrawString("Some text...",
  new XFont("Times New Roman", 12), XBrushes.Firebrick, 50, 100);
// The modified document is saved without any protection applied.
PdfDocumentSecurityLevel level = document.SecuritySettings.DocumentSecurityLevel;
// If you want to save it protected, you must set the DocumentSecurityLevel
// or apply new passwords.
// In the current implementation the old passwords are not automatically
// reused. See 'ProtectDocument' sample for further information.
// Save the document...
// ...and start a viewer.

Here's the source code for the password provider:
/// The 'get the password' call back function.
static void PasswordProvider(PdfPasswordProviderArgs args)
  // Show a dialog here in a real application
  args.Password = "owner";

Note: The samples on this site usually show and discuss code snippets only. The complete source code of the samples with solutions for Visual Studio is available from the download area on CodePlex.