Visual Basic 6.0

Sign PDF with Invisible Signature

See more PDF Signatures Examples

Demonstrates how to sign a PDF with an invisible signature.

Note: This example requires Chilkat v9.5.0.85 or greater.

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.

Dim pdf As New ChilkatPdf

' Load a PDF to be signed.
' The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
success = pdf.LoadFile("qa_data/pdf/hello.pdf")
If (success = 0) Then
    Debug.Print pdf.LastErrorText
    Exit Sub
End If

' Options for signing are specified in JSON.
Dim json As New ChilkatJsonObject

' In most cases, the signingCertificateV2 and signingTime attributes are required.
success = json.UpdateInt("signingCertificateV2",1)
success = json.UpdateInt("signingTime",1)

' Indicate that the signature will be invisible.
success = json.UpdateBool("invisibleSignature",1)

' Load the signing certificate. (Use your own certificate.)
Dim cert As New ChilkatCert
success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret")
If (success = 0) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If

' Tell the pdf object to use the certificate for signing.
success = pdf.SetSigningCert(cert)
If (success = 0) Then
    Debug.Print pdf.LastErrorText
    Exit Sub
End If

success = pdf.SignPdf(json,"qa_output/hello_signed.pdf")
If (success = 0) Then
    Debug.Print pdf.LastErrorText
    Exit Sub
End If

Debug.Print "PDF successfully signed with an invisible signature."

' An invisible signature has no appearance within the PDF document itself,
' but Adobe Acrobat will indicate the document is signed in a toolbar, as shown here:
' (image:https://example-code.com/images/invisible_signature.jpg/endImage)