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CkPython

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

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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.

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CkPython 
import sys
import chilkat

success = False

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

pdf = chilkat.CkPdf()

#  Load a PDF to be signed.
#  The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
success = pdf.LoadFile("qa_data/pdf/hello.pdf")
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

#  Options for signing are specified in JSON.
json = chilkat.CkJsonObject()

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

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

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

jpgData = chilkat.CkBinData()
success = jpgData.LoadFile("qa_data/jpg/university.jpg")
if (success == False):
    print("Failed to load the JPG image.")
    sys.exit()

success = pdf.SetSignatureJpeg(jpgData)
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

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

#  Load the signing certificate. (Use your own certificate.)
cert = chilkat.CkCert()
success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret")
if (success == False):
    print(cert.lastErrorText())
    sys.exit()

#  Tell the pdf object to use the certificate for signing.
success = pdf.SetSigningCert(cert)
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

success = pdf.SignPdf(json,"qa_output/hello_signed.pdf")
if (success == False):
    print(pdf.lastErrorText())
    sys.exit()

print("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