PureBasic

Sign PDF with Long-Term Validation (LTV Enabled)

See more PDF Signatures Examples

This example demonstrates how to a sign a PDF with long-term validation (LTV) enabled.

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

PureBasic

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

Procedure ChilkatExample()

    success.i = 0

    ; 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 = 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)

    ; Add the "ltvOcsp" instruction to the JSON passed to SignPdf.
    ; This is what causes Chilkat to create an LTV-enabled signature.
    ; 
    ; If we are signing a PDF that already has signatures, then the existing signatures
    ; are automatically verified, and Chilkat will do OCSP certificate status checking (if possible) 
    ; for those certs in existing signatures (including certs in the certificate chains) 
    ; that do not yet have a valid OCSP response in the DSS (Document Security Store).
    ; Chilkat will add the OCSP responses to the /OCSPs in the Document Security Store (/DSS).
    ; Also, and certificates from existing signatures not yet in the DSS are added to the /Certs 
    ; in the DSS.
    ; 
    ; Also, the "ltvOcsp" causes Chilkat to add the pdfRevocationInfoArchival authenticated attribute
    ; to the CMS signature.  The pdfRevocationInfoArchival attribute (1.2.840.113583.1.1.8)
    ; contains OCSP responses and the CRL for the issuer of the signing certificate.
    ; Therefore, Chilkat will send an OCSP request to the signing certificate's OCSP URl (if one exists)
    ; and will download the CRL from the issuer certificate's CRL Distribution Point (if one exists).
    CkJsonObject::ckUpdateBool(json,"ltvOcsp",1)

    ; -----------------------------------------------------------------------------------
    ; Note: If Chilkat produces a signed PDF, but the signature is not LTV-enabled,
    ; the cause might be related to a failure to download CRL's or OCSP requests.
    ; See Possible Solution for Failure to Produce LTV-enabled PDF Signature
    ; -----------------------------------------------------------------------------------
    ; You can add the following to UncommonOptions to get detailed information about the CRL and OCSP requests
    ; You shouldn't set the following logging options unless there is a need, because it adds a large amount of information to the LastErrorText.
    CkPdf::setCkUncommonOptions(pdf, "LOG_OCSP_HTTP,LOG_CRL_HTTP")

    ; Define the appearance of the signature.
    CkJsonObject::ckUpdateInt(json,"page",1)
    CkJsonObject::ckUpdateString(json,"appearance.y","top")
    CkJsonObject::ckUpdateString(json,"appearance.x","left")
    CkJsonObject::ckUpdateString(json,"appearance.fontScale","10.0")
    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]","This is an LTV-enabled signature.")

    ; 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","pfxPassword")
    If success = 0
        Debug CkCert::ckLastErrorText(cert)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        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)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

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

    Debug "The PDF has been successfully cryptographically signed with long-term validation."

    ; If you open the Signature Panel in Adobe Acrobat, it will indicate that the signature is LTV enabled
    ; as shown here:
    ; (image:https://example-code.com/images/ltv_signature.jpg/endImage)


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


    ProcedureReturn
EndProcedure