B4X Requires Chilkat v11.7.0+

Encrypt a PDF for a Certificate Instead of a Password

See more PDF Protection Examples

Demonstrates certificate security, where a PDF is encrypted for one or more recipients and each opens it with their own certificate and private key. No password is involved. Only the public certificate of a recipient is needed to encrypt. Each recipient has its own permissions, and the changeSecurity permission gives a recipient owner rights. PreLoadCheck tells an application that a file is certificate-encrypted and which certificates can open it. A PDF that cannot be opened, because no matching certificate and private key were provided, fails to load. B4X

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

'  The recipient's certificate.  Only the public certificate is needed to encrypt.
Dim recipient As ChilkatCert
recipient.Initialize("recipient")
success = recipient.LoadFromFile("qa_data/certs/recipient.cer")
If success = False Then
    Log(recipient.LastErrorText)
    Return
End If


Dim pdf As ChilkatPdf
pdf.Initialize("pdf")
success = pdf.LoadFile("qa_data/pdf/two_page_memo.pdf")
If success = False Then
    Log(pdf.LastErrorText)
    Return
End If


'  Call AddEncryptCert once for each recipient.
success = pdf.AddEncryptCert(recipient)
If success = False Then
    Log(pdf.LastErrorText)
    Return
End If


'  recipientPermissions[0] belongs to the first certificate added.  changeSecurity gives that
'  recipient owner rights, so the file can be managed later.
Dim json As ChilkatJsonObject
json.Initialize
json.UpdateString("method", "certificate")
json.UpdateBool("recipientPermissions[0].changeSecurity", True)

Dim jsonOut As ChilkatJsonObject
jsonOut.Initialize
success = pdf.Protection("encrypt", json, jsonOut)
If success = False Then
    Log(pdf.LastErrorText)
    Return
End If

Log("method: " & jsonOut.StringOf("pending.method"))
Log("algorithm: " & jsonOut.StringOf("pending.algorithm"))
Log("recipients: " & jsonOut.SizeOfArray("pending.recipients"))

success = pdf.WriteFile("qa_output/memo_for_recipient.pdf")
If success = False Then
    Log(pdf.LastErrorText)
    Return
End If


'  PreLoadCheck says how the file is protected, without loading it.
Dim reader As ChilkatPdf
reader.Initialize("reader")
Dim info As ChilkatJsonObject
info.Initialize
success = reader.PreLoadCheck("qa_output/memo_for_recipient.pdf", info)
If success = False Then
    Log(reader.LastErrorText)
    Return
End If

Log("saved file, method: " & info.StringOf("method"))
Log("saved file, recipients: " & info.SizeOfArray("recipients"))

'  The recipient opens it with the certificate and its private key, here from a .pfx file.
'  (On Windows, a certificate that is installed in the Windows certificate store with its private
'  key is found automatically when the PDF is loaded, and SetDecryptCert is not needed for it.)
Dim myCert As ChilkatCert
myCert.Initialize("myCert")
success = myCert.LoadPfxFile("qa_data/pfx/recipient.pfx", "pfx-password")
If success = False Then
    Log(myCert.LastErrorText)
    Return
End If

success = reader.SetDecryptCert(myCert)
If success = False Then
    Log(reader.LastErrorText)
    Return
End If

success = reader.LoadFile("qa_output/memo_for_recipient.pdf")
If success = False Then
    Log(reader.LastErrorText)
    Return
End If


Dim empty As ChilkatJsonObject
empty.Initialize
Dim loadedInfo As ChilkatJsonObject
loadedInfo.Initialize
success = reader.Protection("getInfo", empty, loadedInfo)
If success = False Then
    Log(reader.LastErrorText)
    Return
End If

Log("opened with: " & loadedInfo.StringOf("loaded.openedWith"))
Log("pages: " & reader.NumPages)

'  Sample output:

'  method: certificate
'  algorithm: aes-256
'  recipients: 1
'  saved file, method: certificate
'  saved file, recipients: 1
'  opened with: certificate
'  pages: 2