Xbase++

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.

Xbase++

LOCAL nSuccess
LOCAL oPdf
LOCAL oJson
LOCAL oCert

nSuccess := 0

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

oPdf := CreateObject("Chilkat.Pdf")

//  Load a PDF containing an unsigned signature field.
nSuccess := oPdf:LoadFile("qa_data/pdf/unsigned_sig_field/due_diligence.pdf")
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    RETURN
ENDIF

//  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.
oJson := CreateObject("Chilkat.JsonObject")

//  In most cases, the signingCertificateV2 and signingTime attributes are required.
oJson:UpdateInt("signingCertificateV2", 1)
oJson: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.
oJson: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
oJson: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.
oJson:UpdateString("appearance.text[0]", "Digitally signed by: cert_cn")
oJson:UpdateString("appearance.text[1]", "current_dt")
oJson: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).
oJson:UpdateString("appearance.image", "green-check-grey-circle")
oJson:UpdateString("appearance.imagePlacement", "left")

//  Load the signing certificate. (Use your own certificate.)
oCert := CreateObject("Chilkat.Cert")
nSuccess := oCert:LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx", "secret")
IF (nSuccess == 0)
    ? oCert:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oCert:destroy()
    RETURN
ENDIF

//  Tell the pdf object to use the certificate for signing.
nSuccess := oPdf:SetSigningCert(oCert)
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oCert:destroy()
    RETURN
ENDIF

nSuccess := oPdf:SignPdf(oJson, "qa_output/due_diligence_signed.pdf")
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oCert:destroy()
    RETURN
ENDIF

? "The PDF has been successfully cryptographically signed."

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

oPdf:destroy()
oJson:destroy()
oCert:destroy()