Write QCA Encrypt Decrypt to file

knasan

Hello everybody,

I would like a file with AES locks, for this I use QCA.
Closing seems to work, but I can not decode it anymore. Everything I've tried so far changes the file slightly (another MD5 comes out) or makes it completely useless.

// code to encrypt and write to file.

 QCA::Initializer init = QCA::Initializer();
    if(QCA::isSupported("aes256-cbc-pkcs7"))
    {
        // input filename
        QTextStream streamin(stdin);
        printf("File: ");
        QString filename = streamin.readLine(0);

        QFile inputFile(filename);
        if(!inputFile.open(QIODevice::ReadOnly))
        {
            qDebug() << "problem while reading ";
            return -1;
        }

        const QByteArray ReadFileByteArray = inputFile.readAll();
        inputFile.close();

        qDebug() << "size of clear file" << ReadFileByteArray.size();

        QCA::SecureArray inputSA = ReadFileByteArray;
        qDebug() << "size of inputSA: " << inputSA.size();

        // Password input
        printf("Password: ");
        QString password = streamin.readLine(0);

        QString ki = password;
        QCA::SymmetricKey key = ki.toUtf8();
        QCA::InitializationVector iv = ki.toUtf8();

        QCA::Cipher cipher(QString("aes256"), QCA::Cipher::CBC, QCA::Cipher::DefaultPadding, QCA::Encode, key, iv);

        QCA::SecureArray encoded = cipher.update(inputSA);
        qDebug() << "size of encoded: " << encoded.size();

        if(!cipher.ok())
        {
            qCritical("update failed");
            return -1;
        }

        cipher.setup(QCA::Encode, key, iv);
        QCA::SecureArray original = cipher.process(encoded);
        qDebug() << "size of original" << original.size();

        if(!cipher.ok())
        {
            qCritical("Final failed");
            return -1;
        }

        QByteArray originaldata = original.toByteArray();
        qDebug() << "size of originaldata: " << originaldata.size();

        QString writeFileName = filename + ".e";

        QFile file1(writeFileName);
        if(!file1.open(QIODevice::WriteOnly))
        {
            qCritical("problem while writing ");
            return -1;
        } else {

            QTextStream streamout(&file1);
            streamout << encoded.toByteArray();
            streamout.flush();
        }
        file1.close();

    } else {
        qDebug() << "no";
        qCritical("aes256-cbc-pkcs7");
    }

    return 0;
}

// code to decrypt

 QCA::Initializer init = QCA::Initializer();
    if(QCA::isSupported("aes256-cbc-pkcs7"))
    {

        printf("File: ");
        QTextStream streamin(stdin);
        QString readFileName = streamin.readLine(0);

        printf("Password: ");
        QString password = streamin.readLine(0);

        QString ki = password;
        QCA::SymmetricKey key = ki.toUtf8();
        QCA::InitializationVector iv = ki.toUtf8();
        QCA::Cipher cipher(QString("aes256"), QCA::Cipher::CBC, QCA::Cipher::DefaultPadding, QCA::Encode, key, iv);

        QFile inputFile(readFileName);
        if(!inputFile.open(QIODevice::ReadOnly))
        {
            qCritical("problem while reading");
            return -1;
        }

        const QByteArray ReadFileByteArray = inputFile.readAll();
        inputFile.close();

        cipher.setup(QCA::Decode, key, iv);
        QCA::SecureArray decoded = cipher.update(ReadFileByteArray);

        if(!cipher.ok())
        {
            qCritical("Final failed");
            return -1;
        }

        // wie kann man das Kennwort überprüfen?

        int cutFile = readFileName.length() -2;

        QFile wFile(readFileName.left(cutFile));
        if(!wFile.open(QIODevice::WriteOnly)) {
            qCritical("problem reading file");
            return -1;
        } else {
            /*QTextStream streamout(&wFile);
            streamout << decoded.;
            streamout.flush();*/

            QByteArray original = decoded.toByteArray();

            QString filename = readFileName.left(cutFile);
            QFile wf(filename);
            wf.open(QIODevice::WriteOnly);
            QDataStream out(&wf);
            out << original;
            wf.close();

            wFile.close();
        }

    } else {
        qDebug() << "no";
        qCritical("aes256-cbc-pkcs7");
    }

    return 0;
}

QDataStream does not work at all.
If I use QTextStream, the file can be opened, but not 100 percent the same. Unfortunately, a file.write (data.toByteArray ()) alters the file so that it does not fit 100 percent anymore.

Does anybody know what I'm doing wrong?

Thank you for your help.

SGaist

Hi,

Why not use QFile::write directly rather than the stream operators ?

knasan

Thank you. Directly over QFile :: wirite as ByteArray works without problems. Now all I have to do is find out how to check the password. But for this I make another thread on as soon as I can deal with it.