VB.NET Requires Chilkat v11.7.0+

Password-Protect a PDF with AES-256 Encryption

See more PDF Protection Examples

Demonstrates the simplest way to encrypt a PDF so that it needs a password to open. The passwords come from the UserPassword and OwnerPassword properties, and Protection with the encrypt operation and an empty JSON uses the defaults: AES-256, everything encrypted, every permission granted. Protection only records the security the PDF will be saved with. Nothing is encrypted until WriteFile is called. VB.NET

Dim success As Boolean = False

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

'  The PDF used in this example is available at two_page_memo.pdf

Dim pdf As New Chilkat.Pdf
success = pdf.LoadFile("qa_data/pdf/two_page_memo.pdf")
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If


'  The passwords are taken from these two properties at the time Protection is called.
'  The user password opens the PDF.  The owner password opens it too, and is the one needed
'  later to change or remove the protection.
pdf.UserPassword = "user-secret"
pdf.OwnerPassword = "owner-secret"

'  An empty JSON asks for the defaults: AES-256, everything encrypted, every permission granted.
Dim json As New Chilkat.JsonObject
Dim jsonOut As New Chilkat.JsonObject
success = pdf.Protection("encrypt",json,jsonOut)
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If


'  Nothing has been encrypted yet.  "pending" describes the security the PDF will be saved with.
Debug.WriteLine("algorithm: " & jsonOut.StringOf("pending.algorithm"))
Debug.WriteLine("PDF version: " & jsonOut.StringOf("pending.pdfVersion"))
Debug.WriteLine("password needed to open: " & jsonOut.BoolOf("pending.userPasswordRequired"))

'  Writing the file applies it.
success = pdf.WriteFile("qa_output/memo_encrypted.pdf")
If (success = False) Then
    Debug.WriteLine(pdf.LastErrorText)
    Exit Sub
End If


'  PreLoadCheck reports a file's encryption without loading it, and needs no password.
Dim checker As New Chilkat.Pdf
Dim info As New Chilkat.JsonObject
success = checker.PreLoadCheck("qa_output/memo_encrypted.pdf",info)
If (success = False) Then
    Debug.WriteLine(checker.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("encrypted: " & info.BoolOf("encrypted"))
Debug.WriteLine("openPasswordRequired: " & info.BoolOf("openPasswordRequired"))

'  With the password, the PDF opens normally.
Dim reader As New Chilkat.Pdf
reader.UserPassword = "user-secret"
success = reader.LoadFile("qa_output/memo_encrypted.pdf")
If (success = False) Then
    Debug.WriteLine(reader.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("pages: " & reader.NumPages)

'  Sample output:

'  algorithm: aes-256
'  PDF version: 1.7
'  password needed to open: True
'  encrypted: True
'  openPasswordRequired: True
'  pages: 2