Go Requires Chilkat v11.7.0+

Find Out Whether a PDF Needs a Password Before Loading It

See more PDF Protection Examples

Demonstrates PreLoadCheck, which examines a PDF file without loading it and without any password. It reports whether the file is encrypted, by which method and algorithm, whether a password is needed to open it, and what its permissions are. An application uses it to decide whether to ask for a password, or which certificate it needs, before calling LoadFile. PreLoadCheckBd does the same for a PDF held in memory. 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 PDF used in this example is available at encrypted_user_password.pdf

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

    pdf := chilkat.NewPdf()
    info := chilkat.NewJsonObject()

    //  A PDF that is not encrypted.  Nothing but "encrypted" is reported for it.
    success = pdf.PreLoadCheck("qa_data/pdf/two_page_memo.pdf",info)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        info.DisposeJsonObject()
        return
    }

    fmt.Println("two_page_memo.pdf")
    fmt.Println("  encrypted: ", *info.BoolOf("encrypted"))

    //  A PDF that needs a password to open.
    success = pdf.PreLoadCheck("qa_data/pdf/encrypted_user_password.pdf",info)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        info.DisposeJsonObject()
        return
    }

    fmt.Println("encrypted_user_password.pdf")
    fmt.Println("  encrypted: ", *info.BoolOf("encrypted"))
    fmt.Println("  method: ", *info.StringOf("method"))
    fmt.Println("  algorithm: ", *info.StringOf("algorithm"))
    fmt.Println("  openPasswordRequired: ", *info.BoolOf("openPasswordRequired"))

    //  A PDF that opens without a password but is restricted.  The permissions are readable without
    //  any password.
    success = pdf.PreLoadCheck("qa_data/pdf/no_copy_permission.pdf",info)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        info.DisposeJsonObject()
        return
    }

    fmt.Println("no_copy_permission.pdf")
    fmt.Println("  encrypted: ", *info.BoolOf("encrypted"))
    fmt.Println("  openPasswordRequired: ", *info.BoolOf("openPasswordRequired"))
    fmt.Println("  may copy: ", *info.BoolOf("permissions.copy"))

    //  The typical use: ask for a password only when one is needed, then load.
    success = pdf.PreLoadCheck("qa_data/pdf/encrypted_user_password.pdf",info)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        info.DisposeJsonObject()
        return
    }

    if info.BoolOf("openPasswordRequired") == true {
        //  An application would prompt for the password here.
        pdf.SetUserPassword("secret")
    }

    success = pdf.LoadFile("qa_data/pdf/encrypted_user_password.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        info.DisposeJsonObject()
        return
    }

    fmt.Println("loaded, pages: ", pdf.NumPages())

    //  Sample output:

    //  two_page_memo.pdf
    //    encrypted: False
    //  encrypted_user_password.pdf
    //    encrypted: True
    //    method: password
    //    algorithm: rc4-128
    //    openPasswordRequired: True
    //  no_copy_permission.pdf
    //    encrypted: True
    //    openPasswordRequired: False
    //    may copy: False
    //  loaded, pages: 1

    pdf.DisposePdf()
    info.DisposeJsonObject()