AES Encryptation Length short in my Qt App.

[RojasHenry]

Please I have a problem in Qt-AES library, when I encrypt text multiple times in the same app, I get a text encrypted with less characters, and when I desencrypt in other app not desencrypt it.

[bricke]

Hello, can you provide a sample?

[RojasHenry]

Sorry to answer so late. Ok, I am using the following code to test your algorithm because is important for my project that validate in the server.

I overwrote the following function in your code with my code and add a function to debug the result.

I am using a loop to test your code. the code is making a encrypt and after that desencrypt but it has problem

void Log(char *text){
time_t t = time(NULL);
struct tm *tm = localtime(&t);
FILE *flog;
flog=fopen("./log.txt","a");
char * string_concat = new char[2048];
sprintf(string_concat,"%s : %s\n",strtok(asctime(tm), "\n"),text);
fputs(string_concat,flog);
fclose(flog);
free(string_concat);
}

void AesTest::CBC256StringEvenISO()
{
for(;;){
QString master = QUuid::createUuid().toString().replace(QString("{"),QString("")).replace(QString("}"),QString("")).trimmed();
QString newkey = master.mid(0,32);
//Log(newkey.toLatin1().data());
QString iv = master.right(16);
//Log(iv.toLatin1().data());

    //16 byte string
    QString inputStr("CP017904518010019999CC-17226586200605000840");
    QString inputStrH("QU9qb0FNZ3A0M05jd0FjZ2xBM2FNUHZSU0lSdTJVMER");
    /*QString key("0d133c9d-322f-4937-bbac-cb98e649");
    QString iv("bac-cb98e64919f1");

    //QByteArray hashKey = QCryptographicHash::hash(key.toLatin1(), QCryptographicHash::Sha256);
    //QByteArray hashIV = QCryptographicHash::hash(iv.toLatin1(), QCryptographicHash::Md5);

    QByteArray encodeText = encryption.encode(inputStr.toUtf8(), key.toUtf8(), iv.toUtf8());
    QString stringbase64 = QString::fromLatin1(encodeText.data());
    QString s64 = stringbase64.toLatin1().toBase64();

    QByteArray soTHER = QByteArray::fromBase64(stringbase64.toLatin1().toBase64());
    QByteArray decodeText = encryption.decode(soTHER, key.toUtf8(), iv.toUtf8());
    QString decodedString = QString(encryption.removePadding(decodeText));*/

    QByteArray cabecText = QAESEncryption::Crypt(QAESEncryption::AES_256, QAESEncryption::CBC,inputStr.toUtf8(), newkey.toUtf8(), iv.toUtf8(),QAESEncryption::ZERO);
    QString cabecTextbase64 = QString::fromLatin1(cabecText.data());
    QString cabec64 = cabecTextbase64.toLatin1().toBase64();
    int longitudC = cabec64.length();

    QByteArray huellaText = QAESEncryption::Crypt(QAESEncryption::AES_256, QAESEncryption::CBC,inputStrH.toUtf8(), newkey.toUtf8(), iv.toUtf8(),QAESEncryption::ZERO);
    QString huellaTextbase64 = QString::fromLatin1(huellaText.data());
    QString huella64 = huellaTextbase64.toLatin1().toBase64();
    int longitudH = huella64.length();
    QThread::sleep(1);

    if(longitudC >=64 && longitudH >=64){
        QByteArray cabec64Aux = QByteArray::fromBase64(cabec64.toLatin1());
        QByteArray decodeTextAUX = QAESEncryption::Decrypt(QAESEncryption::AES_256, QAESEncryption::CBC,cabec64Aux, newkey.toUtf8(), iv.toUtf8(),QAESEncryption::ZERO);
        QString decodedcabec = QString(QAESEncryption::RemovePadding(decodeTextAUX,QAESEncryption::ZERO));

        QByteArray huella64Aux = QByteArray::fromBase64(huella64.toLatin1());
        QByteArray decodeTextHAux = QAESEncryption::Decrypt(QAESEncryption::AES_256, QAESEncryption::CBC,huella64Aux, newkey.toUtf8(), iv.toUtf8(),QAESEncryption::ZERO);
        QString decodedhuella = QString(QAESEncryption::RemovePadding(decodeTextHAux,QAESEncryption::ZERO));

        int xC = QString::compare(decodedcabec, inputStr, Qt::CaseSensitive);
        int xH = QString::compare(decodedhuella, inputStrH, Qt::CaseSensitive);

        if(xC == 0 && xH == 0){
            Log("Success with decoding");
        }else{
            Log("Decoding error");
        }
    }else{
        Log("Error size String 64");
    }
}

}
--------------------Result File ----------------------------

[bricke]

I wonder if converting from QString to QByteArray you lose the terminating char that is at the end of the QString? So maybe something gets lost somewhere in those conversions?

[RojasHenry]

it could be, but in this case sometimes work and sometimes doesn't work. Maybe another solution or suggestion please.

[bricke]

My suggestion would be to remove all QStrings and only use QByteArrays, something is happening between conversions, trims and removal of padding.
If it happens only sometimes, that would be my first guess.
Please remember that this is in no way audited and ready for a production environment.

[RojasHenry]

ok, thanks for your suggestions, maybe you know any library to AES 256 instead of your example more trusty for a production environment please.

[bricke]

openssl