Go

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.

Go

    success := false

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

    pdf := chilkat.NewPdf()

    // 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 {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        return
    }

    // Options for signing are specified in JSON.
    json := chilkat.NewJsonObject()

    // In most cases, the signingCertificateV2 and signingTime attributes are required.
    json.UpdateInt("signingCertificateV2",1)
    json.UpdateInt("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).
    json.UpdateBool("ltvOcsp",true)

    // -----------------------------------------------------------------------------------
    // 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.
    pdf.SetUncommonOptions("LOG_OCSP_HTTP,LOG_CRL_HTTP")

    // Define the appearance of the signature.
    json.UpdateInt("page",1)
    json.UpdateString("appearance.y","top")
    json.UpdateString("appearance.x","left")
    json.UpdateString("appearance.fontScale","10.0")
    json.UpdateString("appearance.text[0]","Digitally signed by: cert_cn")
    json.UpdateString("appearance.text[1]","current_dt")
    json.UpdateString("appearance.text[2]","This is an LTV-enabled signature.")

    // Load the signing certificate. (Use your own certificate.)
    cert := chilkat.NewCert()
    success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","pfxPassword")
    if success == false {
        fmt.Println(cert.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        return
    }

    // Tell the pdf object to use the certificate for signing.
    success = pdf.SetSigningCert(cert)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        return
    }

    success = pdf.SignPdf(json,"qa_output/hello_ltv_signed.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        return
    }

    fmt.Println("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)

    pdf.DisposePdf()
    json.DisposeJsonObject()
    cert.DisposeCert()