Visual Basic 6.0 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. Visual Basic 6.0

Dim success As Long
success = 0

'  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 ChilkatPdf
success = pdf.LoadFile("qa_data/pdf/two_page_memo.pdf")
If (success = 0) Then
    Debug.Print 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 ChilkatJsonObject
Dim jsonOut As New ChilkatJsonObject
success = pdf.Protection("encrypt",json,jsonOut)
If (success = 0) Then
    Debug.Print pdf.LastErrorText
    Exit Sub
End If

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

'  Writing the file applies it.
success = pdf.WriteFile("qa_output/memo_encrypted.pdf")
If (success = 0) Then
    Debug.Print pdf.LastErrorText
    Exit Sub
End If

'  PreLoadCheck reports a file's encryption without loading it, and needs no password.
Dim checker As New ChilkatPdf
Dim info As New ChilkatJsonObject
success = checker.PreLoadCheck("qa_output/memo_encrypted.pdf",info)
If (success = 0) Then
    Debug.Print checker.LastErrorText
    Exit Sub
End If

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

'  With the password, the PDF opens normally.
Dim reader As New ChilkatPdf
reader.UserPassword = "user-secret"
success = reader.LoadFile("qa_output/memo_encrypted.pdf")
If (success = 0) Then
    Debug.Print reader.LastErrorText
    Exit Sub
End If

Debug.Print "pages: " & reader.NumPages

'  Sample output:

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