Xojo Plugin

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.

Xojo Plugin

Dim success As Boolean
success = False

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

Dim pdf As New Chilkat.Pdf

// 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 = False) Then
    System.DebugLog(pdf.LastErrorText)
    Return
End If

// Options for signing are specified in JSON.
Dim json As New Chilkat.JsonObject

// 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",True)

// Load the signing certificate. (Use your own certificate.)
Dim cert As New Chilkat.Cert
success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret")
If (success = False) Then
    System.DebugLog(cert.LastErrorText)
    Return
End If

// Tell the pdf object to use the certificate for signing.
success = pdf.SetSigningCert(cert)
If (success = False) Then
    System.DebugLog(pdf.LastErrorText)
    Return
End If

success = pdf.SignPdf(json,"qa_output/hello_signed.pdf")
If (success = False) Then
    System.DebugLog(pdf.LastErrorText)
    Return
End If

System.DebugLog("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)