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Xojo Plugin

PDF Sign Unsigned Signature Field

See more PDF Signatures Examples

Demonstrates how to sign a PDF's unsigned signature field.

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

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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 containing an unsigned signature field.
success = pdf.LoadFile("qa_data/pdf/unsigned_sig_field/due_diligence.pdf")
If (success = False) Then
    System.DebugLog(pdf.LastErrorText)
    Return
End If

//  A PDF with an unsigned signature field appears in Adobe Acrobat as shown below.
//  (When the mouse pointer is hovered over the field, a tooltip will likely show a message
//  such as "Unsigned signature field (Click to sign)".  
//  This example code will automatically find the unsigned signature field,
//  and signs using your certificate.  It automatically sizes the text to the space alotted
//  for the signature.
//  image

//  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)

//  We don't specify the page or a specific location because Chilkat will automatically
//  find the unsigned signature field and use its location and size and will scale the
//  signatures visual appearance (text + graphics) to the correct size required to fit.
//  We only need to indicate the desire to fill the unsigned signature field.
success = json.UpdateBool("appearance.fillUnsignedSignatureField",True)

//  Starting in Chilkat v9.5.0.90, if a PDF contains multiple unsigned signature fields,
//  the field to be signed can be chosen by name:
//  To list unsigned signature fields, see this example: List PDF Unsigned Signature Fields
success = json.UpdateString("unsignedSignatureField","doctor_signature")

//  Note: If the PDF document contains multiple unsigned signature fields, Chilkat will 
//  sign the 1st one found. 

//  In this example, the appearance of the digital signature will contain three lines:
//  1) The signing certificate's common name
//  2) The current date/time
//  3) Some arbitrary text.
//  The keyword "cert_cn" is replaced with the Certificate's Subject Common Name.
//  The keyword "current_dt" is replaced with the current date/time.
//  Any number of appearance text lines can be added.
success = json.UpdateString("appearance.text[0]","Digitally signed by: cert_cn")
success = json.UpdateString("appearance.text[1]","current_dt")
success = json.UpdateString("appearance.text[2]","The crazy brown fox jumps over the lazy dog.")

//  This signature will include one of the built-in SVG graphics (green-check-grey-circle).
success = json.UpdateString("appearance.image","green-check-grey-circle")
success = json.UpdateString("appearance.imagePlacement","left")

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

System.DebugLog("The PDF has been successfully cryptographically signed.")

//  The appearance of the signature appears in Adobe Acrobat as shown below.
//  image