Classic ASP
PDF Sign Unsigned Signature Field

Demonstrates how to sign a PDF's unsigned signature field.
Note: This example requires Chilkat v9.5.0.85 or greater.
Chilkat Classic ASP Downloads

Classic ASP
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

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

set pdf = Server.CreateObject("Chilkat.Pdf")

'  Load a PDF containing an unsigned signature field.
success = pdf.LoadFile("qa_data/pdf/unsigned_sig_field/due_diligence.pdf")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( pdf.LastErrorText) & "</pre>"
    Response.End
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:https://example-code.com/images/unsignedSigField.jpg/endImage)

'  Options for signing are specified in JSON.
set json = Server.CreateObject("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",1)

'  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.)
set cert = Server.CreateObject("Chilkat.Cert")
success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( cert.LastErrorText) & "</pre>"
    Response.End
End If

'  Tell the pdf object to use the certificate for signing.
success = pdf.SetSigningCert(cert)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( pdf.LastErrorText) & "</pre>"
    Response.End
End If

success = pdf.SignPdf(json,"qa_output/due_diligence_signed.pdf")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( pdf.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "The PDF has been successfully cryptographically signed.") & "</pre>"

'  The appearance of the signature appears in Adobe Acrobat as shown below.
'  (image:https://example-code.com/images/signature3.jpg/endImage)

%>
</body>
</html>