Go Requires Chilkat v11.7.0+

Encrypt a PDF for a Certificate Instead of a Password

See more PDF Protection Examples

Demonstrates certificate security, where a PDF is encrypted for one or more recipients and each opens it with their own certificate and private key. No password is involved. Only the public certificate of a recipient is needed to encrypt. Each recipient has its own permissions, and the changeSecurity permission gives a recipient owner rights. PreLoadCheck tells an application that a file is certificate-encrypted and which certificates can open it. A PDF that cannot be opened, because no matching certificate and private key were provided, fails to load. Go

    success := false

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

    //  The PDF used in this example is available at two_page_memo.pdf

    //  The recipient's certificate.  Only the public certificate is needed to encrypt.
    recipient := chilkat.NewCert()
    success = recipient.LoadFromFile("qa_data/certs/recipient.cer")
    if success == false {
        fmt.Println(recipient.LastErrorText())
        recipient.DisposeCert()
        return
    }

    pdf := chilkat.NewPdf()
    success = pdf.LoadFile("qa_data/pdf/two_page_memo.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        recipient.DisposeCert()
        pdf.DisposePdf()
        return
    }

    //  Call AddEncryptCert once for each recipient.
    success = pdf.AddEncryptCert(recipient)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        recipient.DisposeCert()
        pdf.DisposePdf()
        return
    }

    //  recipientPermissions[0] belongs to the first certificate added.  changeSecurity gives that
    //  recipient owner rights, so the file can be managed later.
    json := chilkat.NewJsonObject()
    json.UpdateString("method","certificate")
    json.UpdateBool("recipientPermissions[0].changeSecurity",true)

    jsonOut := chilkat.NewJsonObject()
    success = pdf.Protection("encrypt",json,jsonOut)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        recipient.DisposeCert()
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        return
    }

    fmt.Println("method: ", *jsonOut.StringOf("pending.method"))
    fmt.Println("algorithm: ", *jsonOut.StringOf("pending.algorithm"))
    fmt.Println("recipients: ", jsonOut.SizeOfArray("pending.recipients"))

    success = pdf.WriteFile("qa_output/memo_for_recipient.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        recipient.DisposeCert()
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        return
    }

    //  PreLoadCheck says how the file is protected, without loading it.
    reader := chilkat.NewPdf()
    info := chilkat.NewJsonObject()
    success = reader.PreLoadCheck("qa_output/memo_for_recipient.pdf",info)
    if success == false {
        fmt.Println(reader.LastErrorText())
        recipient.DisposeCert()
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        reader.DisposePdf()
        info.DisposeJsonObject()
        return
    }

    fmt.Println("saved file, method: ", *info.StringOf("method"))
    fmt.Println("saved file, recipients: ", info.SizeOfArray("recipients"))

    //  The recipient opens it with the certificate and its private key, here from a .pfx file.
    //  (On Windows, a certificate that is installed in the Windows certificate store with its private
    //  key is found automatically when the PDF is loaded, and SetDecryptCert is not needed for it.)
    myCert := chilkat.NewCert()
    success = myCert.LoadPfxFile("qa_data/pfx/recipient.pfx","pfx-password")
    if success == false {
        fmt.Println(myCert.LastErrorText())
        recipient.DisposeCert()
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        reader.DisposePdf()
        info.DisposeJsonObject()
        myCert.DisposeCert()
        return
    }

    success = reader.SetDecryptCert(myCert)
    if success == false {
        fmt.Println(reader.LastErrorText())
        recipient.DisposeCert()
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        reader.DisposePdf()
        info.DisposeJsonObject()
        myCert.DisposeCert()
        return
    }

    success = reader.LoadFile("qa_output/memo_for_recipient.pdf")
    if success == false {
        fmt.Println(reader.LastErrorText())
        recipient.DisposeCert()
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        reader.DisposePdf()
        info.DisposeJsonObject()
        myCert.DisposeCert()
        return
    }

    empty := chilkat.NewJsonObject()
    loadedInfo := chilkat.NewJsonObject()
    success = reader.Protection("getInfo",empty,loadedInfo)
    if success == false {
        fmt.Println(reader.LastErrorText())
        recipient.DisposeCert()
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        reader.DisposePdf()
        info.DisposeJsonObject()
        myCert.DisposeCert()
        empty.DisposeJsonObject()
        loadedInfo.DisposeJsonObject()
        return
    }

    fmt.Println("opened with: ", *loadedInfo.StringOf("loaded.openedWith"))
    fmt.Println("pages: ", reader.NumPages())

    //  Sample output:

    //  method: certificate
    //  algorithm: aes-256
    //  recipients: 1
    //  saved file, method: certificate
    //  saved file, recipients: 1
    //  opened with: certificate
    //  pages: 2

    recipient.DisposeCert()
    pdf.DisposePdf()
    json.DisposeJsonObject()
    jsonOut.DisposeJsonObject()
    reader.DisposePdf()
    info.DisposeJsonObject()
    myCert.DisposeCert()
    empty.DisposeJsonObject()
    loadedInfo.DisposeJsonObject()