C++ 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. C++

#include <CkPdf.h>
#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    bool 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

    CkPdf pdf;
    CkJsonObject info;

    //  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) {
        std::cout << pdf.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "two_page_memo.pdf" << "\r\n";
    std::cout << "  encrypted: " << info.BoolOf("encrypted") << "\r\n";

    //  A PDF that needs a password to open.
    success = pdf.PreLoadCheck("qa_data/pdf/encrypted_user_password.pdf",info);
    if (success == false) {
        std::cout << pdf.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "encrypted_user_password.pdf" << "\r\n";
    std::cout << "  encrypted: " << info.BoolOf("encrypted") << "\r\n";
    std::cout << "  method: " << info.stringOf("method") << "\r\n";
    std::cout << "  algorithm: " << info.stringOf("algorithm") << "\r\n";
    std::cout << "  openPasswordRequired: " << info.BoolOf("openPasswordRequired") << "\r\n";

    //  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) {
        std::cout << pdf.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "no_copy_permission.pdf" << "\r\n";
    std::cout << "  encrypted: " << info.BoolOf("encrypted") << "\r\n";
    std::cout << "  openPasswordRequired: " << info.BoolOf("openPasswordRequired") << "\r\n";
    std::cout << "  may copy: " << info.BoolOf("permissions.copy") << "\r\n";

    //  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) {
        std::cout << pdf.lastErrorText() << "\r\n";
        return;
    }

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

    success = pdf.LoadFile("qa_data/pdf/encrypted_user_password.pdf");
    if (success == false) {
        std::cout << pdf.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "loaded, pages: " << pdf.get_NumPages() << "\r\n";

    //  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
    }