(PureBasic) 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 PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkBinData.pb"
IncludeFile "CkCert.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkPdf.pb"

Procedure ChilkatExample()

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

    pdf.i = CkPdf::ckCreate()
    If pdf.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Load a PDF to be signed.
    ; The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
    success.i = CkPdf::ckLoadFile(pdf,"qa_data/pdf/hello.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        ProcedureReturn
    EndIf

    ; Options for signing are specified in JSON.
    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; In most cases, the signingCertificateV2 and signingTime attributes are required.
    CkJsonObject::ckUpdateInt(json,"signingCertificateV2",1)
    CkJsonObject::ckUpdateInt(json,"signingTime",1)

    ; Put the signature on page 1, top left
    CkJsonObject::ckUpdateInt(json,"page",1)
    CkJsonObject::ckUpdateString(json,"appearance.y","top")
    CkJsonObject::ckUpdateString(json,"appearance.x","left")

    ; Use a font scale of 10.0
    CkJsonObject::ckUpdateString(json,"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.
    CkJsonObject::ckUpdateString(json,"appearance.text[0]","Digitally signed by: cert_cn")
    CkJsonObject::ckUpdateString(json,"appearance.text[1]","current_dt")
    CkJsonObject::ckUpdateString(json,"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.i = CkBinData::ckCreate()
    If jpgData.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkBinData::ckLoadFile(jpgData,"qa_data/jpg/university.jpg")
    If success = 0
        Debug "Failed to load the JPG image."
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkBinData::ckDispose(jpgData)
        ProcedureReturn
    EndIf

    success = CkPdf::ckSetSignatureJpeg(pdf,jpgData)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkBinData::ckDispose(jpgData)
        ProcedureReturn
    EndIf

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

    ; Load the signing certificate. (Use your own certificate.)
    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkCert::ckLoadPfxFile(cert,"qa_data/pfx/myPdfSigningCert.pfx","secret")
    If success = 0
        Debug CkCert::ckLastErrorText(cert)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkBinData::ckDispose(jpgData)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; Tell the pdf object to use the certificate for signing.
    success = CkPdf::ckSetSigningCert(pdf,cert)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkBinData::ckDispose(jpgData)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    success = CkPdf::ckSignPdf(pdf,json,"qa_output/hello_signed.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkBinData::ckDispose(jpgData)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    Debug "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.
    


    CkPdf::ckDispose(pdf)
    CkJsonObject::ckDispose(json)
    CkBinData::ckDispose(jpgData)
    CkCert::ckDispose(cert)


    ProcedureReturn
EndProcedure