DataFlex

PDF Sign Under Existing Signature

See more PDF Signatures Examples

This example explains how sign a previously-signed PDF and place the signature appearance below the existing signature.

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

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoPdf
    Variant vJson
    Handle hoJson
    Variant vCert
    Handle hoCert
    String sTemp1

    Move False To iSuccess

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

    Get Create (RefClass(cComChilkatPdf)) To hoPdf
    If (Not(IsComObjectCreated(hoPdf))) Begin
        Send CreateComObject of hoPdf
    End

    //  Load a PDF to be signed.
    Get ComLoadFile Of hoPdf "qa_data/pdf/sign_testing_4/hello_signed.pdf" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoPdf To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  The PDF we'll be signing already has a signature added in Adobe Acrobat DC.
    //  It looks like this:
    //  (Notice the Adobe background logo, which is commonly what you'll see when a signature
    //  is created by Adobe Acrobat.  Chilkat (obviously) does not create signatures using the Adobe
    //  logo because it would be a copyright violation.)

    //  

    //  Options for signing are specified in JSON.
    Get Create (RefClass(cComChilkatJsonObject)) To hoJson
    If (Not(IsComObjectCreated(hoJson))) Begin
        Send CreateComObject of hoJson
    End

    //  In most cases, the signingCertificateV2 and signingTime attributes are required.
    Get ComUpdateInt Of hoJson "signingCertificateV2" 1 To iSuccess
    Get ComUpdateInt Of hoJson "signingTime" 1 To iSuccess

    //  To put our new signature underneath the existing signature, we have to specify the page
    //  where the existing signature is found, and then we can specify "under" for the "appearance.y"
    Get ComUpdateInt Of hoJson "page" 1 To iSuccess
    Get ComUpdateString Of hoJson "appearance.y" "under" To iSuccess

    Get ComUpdateString Of hoJson "appearance.fontScale" "10.0" To iSuccess

    Get ComUpdateString Of hoJson "appearance.text[0]" "Reason: Agreement Accepted by John" To iSuccess
    Get ComUpdateString Of hoJson "appearance.text[1]" "Date: current_dt" To iSuccess

    //  Load the signing certificate. (Use your own certificate.)
    Get Create (RefClass(cComChilkatCert)) To hoCert
    If (Not(IsComObjectCreated(hoCert))) Begin
        Send CreateComObject of hoCert
    End
    Get ComLoadPfxFile Of hoCert "qa_data/pfx/myPdfSigningCert.pfx" "secret" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCert To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Tell the pdf object to use the certificate for signing.
    Get pvComObject of hoCert to vCert
    Get ComSetSigningCert Of hoPdf vCert To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoPdf To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Note: When adding an additional signature to a PDF, the existing signatures
    //  are validated, and this includes validating the certificates previously used to 
    //  create the existing signatures.  (A signature typically embeds the signing certs.)
    //  In some cases, the certificates and/or certs in the chain of authentication for 
    //  existing signatures are not present, and are not available on the current system.
    //  In this case, you can skip the validation by setting this keyword in UncommonOptions:
    Set ComUncommonOptions Of hoPdf To "NO_VERIFY_CERT_SIGNATURES"

    Get pvComObject of hoJson to vJson
    Get ComSignPdf Of hoPdf vJson "qa_output/hello_signed.pdf" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoPdf To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "The PDF has been successfully cryptographically signed."

    //  Here's a screenshot of the 2nd signature positioned under the 1st in Adobe Acrobat:

    //  


End_Procedure