Qt encryption, QCA build error

gaminn

Hello,
Is there any simple encryption algorithm for mingw like:

EncryptedData = Encrypt(DataToBeEncrypted, Key);

EncryptedData, DataToBeEncrypted and Key should be 16 to 32 bytes long. There is no need of data decryption later.

I tried to do this using Crypto++ AES, however, it's quite difficult to understand that library for me.

Thank you

vezprog

I can recall a previous post that one of the moderators linked his encryption class to someone. I dont know if this is what your looking for, but it might help.

http://qt-project.org/forums/viewthread/4565
http://qt-project.org/wiki/Simple_encryption

andre

Thanks for the reference :-)

Heed the warning at the top though: it does not count as strong encryption, but if you read the discussion it not trivial to break either.

tucnak

I recommend you QCA (Qt Cryptographic Archetecture) to encrypt/decrypt in Qt.

ObiWan

Take a look at "PolarSSL":http://polarssl.org/.
It's simple to build an simple to use.
I also tried Crypto++ and decided for PolarSSL in the end.

tobias.hunger

If you don't want to decrypt again, then you basically want a hash. QCryptographicHash might be what you need then. The algorithmns offered are not the newest, but they might suffice for your needs. Just hash your key followed by your data and you should be fine.

gaminn

Thank you all for your replies.

Tobias Hunger: The hash is not what I want. There must be the key: EncryptedData = Encrypt(DataToBeEncrypted, Key);

I tried to use QCA - I downloaded binaries http://delta.affinix.com/download/qca/2.0/qca-2.0.1-mingw.zip , but when I run simple test program (with libqcad2.a), it crashes: "During startup program exites with code 0xc0000135".

I also tried to build QCA using this tutorial: http://www.essentialunix.org/index.php?option=com_content&view=article&id=48:qcatutorial&catid=34:qttutorials&Itemid=53

I can run configure.exe and qmake.exe commands, but when running mingw32-make I get error (QtGlobal include file not found):

In file included from botantools\botan/botan/util.h:37,
from botantools\botan\util.cpp:34:
botantools\botan/botan/types.h:38:20: error: QtGlobal: No such file or directory

In file included from botantools\botan/botan/util.h:37,
from botantools\botan\util.cpp:34:
botantools\botan/botan/types.h:50: error: 'quint8' does not name a type
botantools\botan/botan/types.h:51: error: 'quint16' does not name a type
botantools\botan/botan/types.h:52: error: 'quint32' does not name a type
botantools\botan/botan/types.h:53: error: 'qint32' does not name a type
botantools\botan/botan/types.h:54: error: 'quint64' does not name a type
botantools\botan/botan/types.h:80: error: 'byte' in namespace 'QCA::Botan' does
not name a type
botantools\botan/botan/types.h:81: error: 'u32bit' in namespace 'QCA::Botan' doe
s not name a type

Please can you advise?

gaminn

OK, somehow I managed to build http://delta.affinix.com/download/qca/2.0/qca-2.0.3.tar.bz2.

Now I need to build http://delta.affinix.com/download/qca/2.0/plugins/qca-ossl-2.0.0-beta3.tar.bz2 (because I need AES). I again use this tutorial: http://www.essentialunix.org/index.php?option=com_content&view=article&id=48:qcatutorial&catid=34:qttutorials&Itemid=53

I installed OpenSSL, made directory tree:

C:\local
C:\local\bin
C:\local\include
C:\local\lib

Copied and renamed the files.

Ran:

echo "WINLOCAL_PREFIX = C:/local" > %QTDIR%\mkspecs\features\winlocal.prf
configwin rd
qmake

Then, ming32-make produces this error:

C:\SOURCE\Library\Qt\qca\qca-ossl>C:\QtSDK\mingw\bin\mingw32-make.exe
C:/QtSDK/mingw/bin/mingw32-make -f Makefile.Release all
mingw32-make[1]: Entering directory C:/SOURCE/Library/Qt/qca/qca-ossl' C:\iwmake\build_mingw_opensource\bin\moc.exe -DUNICODE -DQT_LARGEFILE_SUPPORT -D OSSL_097 -DQT_NO_DEBUG -DQT_PLUGIN -DQT_CORE_LIB -DQT_THREAD_SUPPORT -DQT_NO_DYN AMIC_CAST -I"c:\iwmake\build_mingw_opensource\include\QtCore" -I"c:\iwmake\build _mingw_opensource\include" -I"c:\local\include" -I"..\include\QtCrypto" -I"c:\iw make\build_mingw_opensource\include\ActiveQt" -I"release" -I"c:\Qt\4.8.2\mkspecs \win32-g++" -D__GNUC__ -DWIN32 qca-ossl.cpp -o release\qca-ossl.moc Systém nemůže nalézt uvedenou cestu. = {translation: Can't find specified path} mingw32-make[1]: *** [release/qca-ossl.moc] Error 1 mingw32-make[1]: Leaving directory C:/SOURCE/Library/Qt/qca/qca-ossl'
mingw32-make: *** [release-all] Error 2

There is "c:\iwmake" path mentioned in this error, but this path doesn't exist on my computer. Is this the source of the error? How to fix it?

Thank you#

gaminn

Spent 5 hours bulding QCA but finally did it! The problem was - Don't run C:\QtSDK\mingw\bin\mingw32-make.exe, simply type mingw32-make.

I'm a windows user used to compile my programs in graphical IDEs by clicking Run button, so building sources using command prompt is quite exotic for me and I don't understand it very well. Is there any literature I can read about compiling from command prompt?

DerManu

bq. Tobias Hunger: The hash is not what I want. There must be the key: EncryptedData = Encrypt(DataToBeEncrypted, Key);

What's the difference between
Encrypt(Data, Key)
and
Hash(Data+Key)
When you don't need decryption?
Looks to me as if you're using something wrong here, what's the overall purpose of this?

gaminn

I made a TCP client and server and need client to authorize when connecting to server.

When connection is established, server sends a question to client. The question is 256 bit long integer.
Client receives the question and makes reply: ClientReply = Encrypt(Question, Key).
Servers received ClientReply and if it is allright, the client is aurhorized. Server increments question.

I think it is enough to satisfy my security demands :)

DerManu

Well then a Hash is definetly the right thing and an encryption is definetly the wrong thing to use.
Further one shouldn't make up own security/authorization protocols when not proficient in it. Your scheme looks like it's vulnerable to replay attacks (due to the determinism in "Server increments question").

Make your application work with the standard mechanisms in the field:
https://en.wikipedia.org/wiki/Cryptographic_nonce
https://en.wikipedia.org/wiki/Cryptographic_salt