Decrypt and Encrypt PDF files in C# and VB.NET
You can use PDF encryption as a security mechanism to:
- Allow only the people that know the password to view your PDF.
- Prohibit anyone to print or edit your PDF, which is enforced by the PDF viewer/editor application.
With GemBox.Pdf, you can perform the following PDF encryption scenarios in your C# or VB.NET application:
With the examples below, you will be able to understand how to use GemBox.Pdf for each of those scenarios. See the example below to learn how to encrypt an existing PDF file with a password. As shown in the screenshot from above, the output PDF file has a Password Security method and Document Open Password is required to open a PDF file. You can perform all operations except page extraction. The Restrict Editing example shows how to modify user access permissions. The PDF encryption level is 128-bit AES and is supported in Adobe Acrobat 7.0 and later. All contents of the document are encrypted, including metadata (used by search engines). The Encryption Settings example shows how to modify the encryption level and options. The following example shows how to decrypt a password-encrypted PDF file. To decrypt a PDF file when loading a PDF document, either the If the input PDF file is not encrypted or is encrypted but with an empty Note that GemBox.Pdf verifies the password only when the first This behavior enables you to extract some useful information from an encrypted PDF file without knowing its If you need to restrict users from editing PDF files, see the example below. PDF encryption enables the enforcement of various user access permissions. In the example above, users can only print a document and fill in an interactive form if it exists in the file. Applications can copy text and graphics for accessibility, as an example, to users with disabilities. Note that the PDF viewer/editor does the enforcement of user access permissions. You can open and bypass those restrictions in a PDF file by using applications that do not respect PDF specification requirements. GemBox.Pdf does not respect PDF specification requirements regarding user access permissions because it is not an end-user application. Also keep in mind that although a PDF file is encrypted, a password is not necessary to open it. The following example shows how to encrypt an existing PDF file using various encryption settings. The first part of this example is a combination of Encrypt and Restrict Editing examples so a password (either the The last part of this example shows how to set the encryption to the strongest level currently supported by PDF password-based encryption – 256-bit AES supported by Adobe Acrobat X and later. It also shows how to specify which parts of a PDF file should be encrypted. In this example, the document's metadata stream is excluded from encryption so search engines will be able to access it.Encrypt a PDF file
using GemBox.Pdf;
class Program
{
static void Main()
{
// If using the Professional version, put your serial key below.
ComponentInfo.SetLicense("FREE-LIMITED-KEY");
// Load PDF document from an unencrypted PDF file.
using (var document = PdfDocument.Load("%InputFileName%"))
{
// Set password-based encryption with password required to open a PDF document.
document.SaveOptions.SetPasswordEncryption().DocumentOpenPassword = "%DocumentOpenPassword%";
// Save PDF document to an encrypted PDF file.
document.Save("Encryption.pdf");
}
}
}Imports GemBox.Pdf
Module Program
Sub Main()
' If using the Professional version, put your serial key below.
ComponentInfo.SetLicense("FREE-LIMITED-KEY")
' Load PDF document from an unencrypted PDF file.
Using document = PdfDocument.Load("%InputFileName%")
' Set password-based encryption with password required to open a PDF document.
document.SaveOptions.SetPasswordEncryption().DocumentOpenPassword = "%DocumentOpenPassword%"
' Save PDF document to an encrypted PDF file.
document.Save("Encryption.pdf")
End Using
End Sub
End ModuleDecrypt a PDF file
using System;
using GemBox.Pdf;
using GemBox.Pdf.Security;
class Program
{
static void Main()
{
// If using the Professional version, put your serial key below.
ComponentInfo.SetLicense("FREE-LIMITED-KEY");
try
{
// Load PDF document from a potentially encrypted PDF file.
using (var document = PdfDocument.Load("%InputFileName%",
new PdfLoadOptions() { Password = "%DocumentOpenPassword%" }))
{
// Remove encryption from an output PDF file.
document.SaveOptions.Encryption = null;
// Save PDF document to an unencrypted PDF file.
document.Save("Decryption.pdf");
}
}
catch (InvalidPdfPasswordException ex)
{
// Gracefully handle the case when input PDF file is encrypted
// and provided password is invalid.
Console.WriteLine(ex.Message);
}
}
}Imports System
Imports GemBox.Pdf
Imports GemBox.Pdf.Security
Module Program
Sub Main()
' If using the Professional version, put your serial key below.
ComponentInfo.SetLicense("FREE-LIMITED-KEY")
Try
' Load PDF document from a potentially encrypted PDF file.
Using document = PdfDocument.Load("%InputFileName%",
New PdfLoadOptions() With {.Password = "%DocumentOpenPassword%"})
' Remove encryption from an output PDF file.
document.SaveOptions.Encryption = Nothing
'Save PDF document to an unencrypted PDF file.
document.Save("Decryption.pdf")
End Using
Catch ex As InvalidPdfPasswordException
' Gracefully handle the case when input PDF file is encrypted
' and provided password is invalid.
Console.WriteLine(ex.Message)
End Try
End Sub
End ModuleDocumentOpenPassword or the PermissionsPassword must be specified in the PdfLoadOptions.Password property. If the specified password is invalid, then an InvalidPdfPasswordException is thrown.DocumentOpenPassword (like in the Restrict Editing example), then the password specified in the PdfLoadOptions.Password property is not used.PdfString or PdfStream from an encrypted PDF file has to be read, since only strings and streams are subject to encryption, based on the PDF specification. As a consequence, an InvalidPdfPasswordException might be thrown after the loading of a PDF document.DocumentOpenPassword password, like number of pages or other information that doesn't directly reference any PdfString or PdfStream.Restrict editing of a PDF file
using GemBox.Pdf;
using GemBox.Pdf.Security;
class Program
{
static void Main()
{
// If using the Professional version, put your serial key below.
ComponentInfo.SetLicense("FREE-LIMITED-KEY");
// Load PDF document from an unencrypted PDF file.
using (var document = PdfDocument.Load("%InputFileName%"))
{
// Set password-based encryption to an output PDF file.
var encryption = document.SaveOptions.SetPasswordEncryption();
// Specify password required to edit a PDF document.
encryption.PermissionsPassword = "%PermissionsPassword%";
// User will be able to print PDF and fill-in PDF form
// without requiring a password.
encryption.Permissions =
PdfUserAccessPermissions.Print |
PdfUserAccessPermissions.FillForm |
PdfUserAccessPermissions.CopyContentForAccessibility |
PdfUserAccessPermissions.PrintHighResolution;
// Save PDF document to an encrypted PDF file.
document.Save("Restrict Editing.pdf");
}
}
}Imports GemBox.Pdf
Imports GemBox.Pdf.Security
Module Program
Sub Main()
' If using the Professional version, put your serial key below.
ComponentInfo.SetLicense("FREE-LIMITED-KEY")
' Load PDF document from an unencrypted PDF file.
Using document = PdfDocument.Load("%InputFileName%")
' Set password-based encryption to an output PDF file.
Dim encryption = document.SaveOptions.SetPasswordEncryption()
' Specify password required to edit a PDF document.
encryption.PermissionsPassword = "%PermissionsPassword%"
' User will be able to print PDF and fill-in PDF form
' without requiring a password.
encryption.Permissions =
PdfUserAccessPermissions.Print Or
PdfUserAccessPermissions.FillForm Or
PdfUserAccessPermissions.CopyContentForAccessibility Or
PdfUserAccessPermissions.PrintHighResolution
' Save PDF document to an encrypted PDF file.
document.Save("Restrict Editing.pdf")
End Using
End Sub
End ModuleSpecify encryption settings
using GemBox.Pdf;
using GemBox.Pdf.Security;
class Program
{
static void Main()
{
// If using the Professional version, put your serial key below.
ComponentInfo.SetLicense("FREE-LIMITED-KEY");
// Load PDF document from an unencrypted PDF file.
using (var document = PdfDocument.Load("%InputFileName%"))
{
// Set password-based encryption to an output PDF file.
var encryption = document.SaveOptions.SetPasswordEncryption();
// Specify password required to open a PDF document.
encryption.DocumentOpenPassword = "%DocumentOpenPassword%";
// Specify password required to edit a PDF document.
encryption.PermissionsPassword = "%PermissionsPassword%";
// User will be able to print PDF and fill-in PDF form
// without requiring a password.
encryption.Permissions =
PdfUserAccessPermissions.Print |
PdfUserAccessPermissions.FillForm |
PdfUserAccessPermissions.CopyContentForAccessibility |
PdfUserAccessPermissions.PrintHighResolution;
// Specify 256-bit AES encryption level (supported in Acrobat X and later).
encryption.EncryptionLevel = new PdfEncryptionLevel(PdfEncryptionAlgorithm.AES, 256);
// Encrypt content and embedded files but do not encrypt document's metadata.
encryption.Options = PdfEncryptionOptions.EncryptContent | PdfEncryptionOptions.EncryptEmbeddedFiles;
// Save PDF document to an encrypted PDF file.
document.Save("Encryption Settings.pdf");
}
}
}Imports GemBox.Pdf
Imports GemBox.Pdf.Security
Module Program
Sub Main()
' If using the Professional version, put your serial key below.
ComponentInfo.SetLicense("FREE-LIMITED-KEY")
' Load PDF document from an unencrypted PDF file.
Using document = PdfDocument.Load("%InputFileName%")
' Set password-based encryption to an output PDF file.
Dim encryption = document.SaveOptions.SetPasswordEncryption()
' Specify password required to open a PDF document.
encryption.DocumentOpenPassword = "%DocumentOpenPassword%"
' Specify password required to edit a PDF document.
encryption.PermissionsPassword = "%PermissionsPassword%"
' User will be able to print PDF and fill-in PDF form
' without requiring a password.
encryption.Permissions =
PdfUserAccessPermissions.Print Or
PdfUserAccessPermissions.FillForm Or
PdfUserAccessPermissions.CopyContentForAccessibility Or
PdfUserAccessPermissions.PrintHighResolution
' Specify 256-bit AES encryption level (supported in Acrobat X and later).
encryption.EncryptionLevel = New PdfEncryptionLevel(PdfEncryptionAlgorithm.AES, 256)
' Encrypt content and embedded files but do not encrypt document's metadata.
encryption.Options = PdfEncryptionOptions.EncryptContent Or PdfEncryptionOptions.EncryptEmbeddedFiles
' Save PDF document to an encrypted PDF file.
document.Save("Encryption Settings.pdf")
End Using
End Sub
End ModuleDocumentOpenPassword or the PermissionsPassword) will be required to open a document and only users who entered a PermissionsPassword will be able to edit a document in a PDF editor application.
