(Lianja) 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.

Chilkat Lianja Extension Download Chilkat Lianja Extension

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

loPdf = createobject("CkPdf")

// Load a PDF to be signed.
// The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
llSuccess = loPdf.LoadFile("qa_data/pdf/hello.pdf")
if (llSuccess = .F.) then
    ? loPdf.LastErrorText
    release loPdf
    return
endif

// Options for signing are specified in JSON.
loJson = createobject("CkJsonObject")

// In most cases, the signingCertificateV2 and signingTime attributes are required.
loJson.UpdateInt("signingCertificateV2",1)
loJson.UpdateInt("signingTime",1)

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

// Use a font scale of 10.0
loJson.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.
loJson.UpdateString("appearance.text[0]","Digitally signed by: cert_cn")
loJson.UpdateString("appearance.text[1]","current_dt")
loJson.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

loJpgData = createobject("CkBinData")
llSuccess = loJpgData.LoadFile("qa_data/jpg/university.jpg")
if (llSuccess = .F.) then
    ? "Failed to load the JPG image."
    release loPdf
    release loJson
    release loJpgData
    return
endif

llSuccess = loPdf.SetSignatureJpeg(loJpgData)
if (llSuccess = .F.) then
    ? loPdf.LastErrorText
    release loPdf
    release loJson
    release loJpgData
    return
endif

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

// Load the signing certificate. (Use your own certificate.)
loCert = createobject("CkCert")
llSuccess = loCert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret")
if (llSuccess = .F.) then
    ? loCert.LastErrorText
    release loPdf
    release loJson
    release loJpgData
    release loCert
    return
endif

// Tell the pdf object to use the certificate for signing.
llSuccess = loPdf.SetSigningCert(loCert)
if (llSuccess = .F.) then
    ? loPdf.LastErrorText
    release loPdf
    release loJson
    release loJpgData
    release loCert
    return
endif

llSuccess = loPdf.SignPdf(loJson,"qa_output/hello_signed.pdf")
if (llSuccess = .F.) then
    ? loPdf.LastErrorText
    release loPdf
    release loJson
    release loJpgData
    release loCert
    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.



release loPdf
release loJson
release loJpgData
release loCert