Visual Basic 6.0 Requires Chilkat v11.7.0+

Change the Permissions of an Encrypted PDF

See more PDF Protection Examples

Demonstrates the changePermissions operation, which changes what an encrypted PDF permits and keeps its passwords, algorithm and scope. The JSON takes the same permissions member as the encrypt operation, and a permission that is not mentioned is granted. The operation needs owner rights. For an AES-256 PDF, load with both passwords, because the user password cannot be recovered from the owner password alone. 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 encrypted_user_password.pdf

Dim pdf As New ChilkatPdf

'  Changing the permissions needs owner rights.  Both passwords are given here, which is what
'  an AES-256 PDF requires for this operation.
pdf.UserPassword = "secret"
pdf.OwnerPassword = "owner-secret"
success = pdf.LoadFile("qa_data/pdf/encrypted_user_password.pdf")
If (success = 0) Then
    Debug.Print pdf.LastErrorText
    Exit Sub
End If

'  No printing and no copying.  Everything not mentioned is granted.
Dim json As New ChilkatJsonObject
success = json.UpdateString("permissions.print","none")
success = json.UpdateBool("permissions.copy",0)

Dim jsonOut As New ChilkatJsonObject
success = pdf.Protection("changePermissions",json,jsonOut)
If (success = 0) Then
    Debug.Print pdf.LastErrorText
    Exit Sub
End If

Debug.Print "print: " & jsonOut.StringOf("pending.permissions.print")
Debug.Print "copy: " & jsonOut.BoolOf("pending.permissions.copy")
Debug.Print "modify: " & jsonOut.BoolOf("pending.permissions.modify")
Debug.Print "password still needed to open: " & jsonOut.BoolOf("pending.userPasswordRequired")

success = pdf.WriteFile("qa_output/minutes_no_print.pdf")
If (success = 0) Then
    Debug.Print pdf.LastErrorText
    Exit Sub
End If

'  The same user password opens the result, now with the new permissions.
Dim reader As New ChilkatPdf
reader.UserPassword = "secret"
success = reader.LoadFile("qa_output/minutes_no_print.pdf")
If (success = 0) Then
    Debug.Print reader.LastErrorText
    Exit Sub
End If

Dim empty As New ChilkatJsonObject
Dim info As New ChilkatJsonObject
success = reader.Protection("getInfo",empty,info)
If (success = 0) Then
    Debug.Print reader.LastErrorText
    Exit Sub
End If

Debug.Print "saved file, print: " & info.StringOf("loaded.permissions.print")
Debug.Print "saved file, copy: " & info.BoolOf("loaded.permissions.copy")

'  Sample output:

'  print: none
'  copy: False
'  modify: True
'  password still needed to open: True
'  saved file, print: none
'  saved file, copy: False