Xbase++

PDF Signature with Background Image (Seal/Stamp/etc.)

See more PDF Signatures Examples

Demonstrates how to sign a PDF with an appearance that includes a background image, such as a seal, stamp, etc.

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

Xbase++

LOCAL nSuccess
LOCAL oPdf
LOCAL oJson
LOCAL oJpgData
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 to be signed.
//  The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
nSuccess := oPdf:LoadFile("qa_data/pdf/hello.pdf")
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    RETURN
ENDIF

//  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)

//  Put the signature on page 1, top left
oJson:UpdateInt("page", 1)
oJson:UpdateString("appearance.y", "top")
oJson:UpdateString("appearance.x", "left")

//  Use a font scale of 10.0
oJson:UpdateString("appearance.fontScale", "10.0")

//  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.")

//  Load a JPG image to be shown with 30% opacity in the background.
//  (the image must be in the JPG format)
//  The sample university.jpb is available at https://example-code.com/images/university.jpg

oJpgData := CreateObject("Chilkat.BinData")
nSuccess := oJpgData:LoadFile("qa_data/jpg/university.jpg")
IF (nSuccess == 0)
    ? "Failed to load the JPG image."
    oPdf:destroy()
    oJson:destroy()
    oJpgData:destroy()
    RETURN
ENDIF

nSuccess := oPdf:SetSignatureJpeg(oJpgData)
IF (nSuccess == 0)
    ? oPdf:LastErrorText
    oPdf:destroy()
    oJson:destroy()
    oJpgData:destroy()
    RETURN
ENDIF

//  Specify that we want to display the JPG image in the center with 30% opacity.
oJson:UpdateString("appearance.image", "custom-jpg")
oJson:UpdateString("appearance.imagePlacement", "center")
oJson:UpdateString("appearance.imageOpacity", "30")

//  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()
    oJpgData: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()
    oJpgData:destroy()
    oCert:destroy()
    RETURN
ENDIF

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

? "The PDF has been successfully cryptographically signed."

//  The appearance of the signature appears in Adobe Acrobat as shown below.
//  The JPG is automatically scaled to the size of the signature based on the signature's font scale
//  and number of text lines.
//  (image:https://example-code.com/images/signature2.jpg/endImage)

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