(PowerShell) 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.

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Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

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

$pdf = New-Object Chilkat.Pdf

# 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 -eq $false) {
    $($pdf.LastErrorText)
    exit
}

# Options for signing are specified in JSON.
$json = New-Object Chilkat.JsonObject

# 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 = New-Object Chilkat.BinData
$success = $jpgData.LoadFile("qa_data/jpg/university.jpg")
if ($success -eq $false) {
    $("Failed to load the JPG image.")
    exit
}

$success = $pdf.SetSignatureJpeg($jpgData)
if ($success -eq $false) {
    $($pdf.LastErrorText)
    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 = New-Object Chilkat.Cert
$success = $cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret")
if ($success -eq $false) {
    $($cert.LastErrorText)
    exit
}

# Tell the pdf object to use the certificate for signing.
$success = $pdf.SetSigningCert($cert)
if ($success -eq $false) {
    $($pdf.LastErrorText)
    exit
}

$success = $pdf.SignPdf($json,"qa_output/hello_signed.pdf")
if ($success -eq $false) {
    $($pdf.LastErrorText)
    exit
}

$("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.