Monthly Archives: September 2011

Windows 8 Developer Preview on Qemu

The Windows 8 Developer Preview installs easily on Qemu 0.14.1 on Ubuntu.

$ qemu-system-i386 -m 1024 -vga std -net nic -net user -cdrom w8.iso c.qcow2

Performance is… not good at all, but completely possible to get an impression of Windows 8 and Metro.

This is the x86 version – I have not completed the x64 version at this time. I will get back about the 64-bit version with developer tools.

Update: Well, the released version of Windows 8 is not very impressive. I think I lost my curiosity for WinRT for now. Perhaps my curiosity will awaken again, but for now I think my Windows 8 experimentation is over.

For those of you who want an idea… when you click “Start” to get the start menu, instead you get the full screen Metro interface where you start applications. And it starts with this Metro in full screen. And to get to the desktop, you start the Explorer application from the Metro interface. I think the start menu got larger in every version of Windows since NT4, and I never liked it. I don’t like it this time either.

Build QT/Symbian Apps on Linux/Mac OS X

QT is a nice cross plattform development environment, but building for Symbian is a bit tricky on non Windows platforms. Or is it?

You can Google for it, and find information about Gnupoc, Gcce and building qt for ARM with tools that require WINE. Not trivial.

You can also find occational references to an experimental feature called “remote compiler” – sounds like you need a Window machine, doesn’t it?

No – it is really easy! You need a Nokia Developer account (which takes 5 minutes to set up, and costs nothing). Then you configure QtCreator to use the remote compiler – and it sends your code to Nokia, who compiles it, and returns you errors, warnings and binaries. Compilation-as-service? Fine with me!

To get it working, I suggest you install the full QT SDK (not just QtCreator), and you need to choose “Custom” installation, and under Experimental you pick Remote Compiler.

Next, when you have opened your project in QtCreator, you click the “Projects” button to the left. Now, in the top of your work area, there are boxes with build targets, and to the right of the targets a “+”-sign. Click it. Choose remote compiler, target platforms and other options. To deploy it to your phone, you need to choose to sign the application, and to use the smart installer.

Quickly and easily transfer files over network

You want to copy a file between two computers or Symbian phones, and the usual methods don’t feel that attractive? Network drives, scp and ftp requires configuring a server (that later might be a security risk). USB cables are never available when needed. DropBox and Bluetooth are too slow.

A while ago I described how to copy files with netcat, but that works best on *nix and is not so easy for people who do not like the command line. And, it does not work on mobile phones.

So, I wrote a little program that does what netcat does but is simple to use and has a GUI. And, I wrote it in QT, so it works in Mac OS X, Linux, Windows and Symbian. It is exactly the same on all platforms.

Do you want a simple way to copy files over the network? Download ParrotCopy and give it a try – instructions included:


The Symbian version probably only works on Symbian^3 and has just been tested on Nokia N8. Let me know if you need a binary for an older Symbian device or a Maemo or Harmattan device.

In server mode, the program tries to connect to, to figure out its own IP. It is simply an ugly hack because I had problems with other methods. You may have problems if internet is not accessible. I will not release 1.0 until this is fixed.

You have to manually name the file you receive, and you can transfer just one file at a time. These are not bugs, but future versions will probably do better. Netcat can be combined with tar, gzip etc. I hope to add at least tar in the future. For now, making a zipfile is a simple way to transfer many files.

Release 0.9.7
Now possible to copy contents of status field and file/folder fields (if you want to paste it into other application).

Make Xcode 3.2.6 gcc work

Apple did something smart around Xcode 3.2.6 – probably to make it easy to configure gcc to use different SDKs. But, before figuring out what happened, it just brakes your compiler. With Xcode 3.2.6 (and maybe later versions):

sleipnir:~ gt$ cat hello.c 

int main() {
    printf("Hello world\n");

sleipnir:~ gt$ gcc -o hello hello.c
-bash: gcc: command not found
sleipnir:~ gt$ PATH=/Developer/usr/bin/:$PATH
sleipnir:~ gt$ gcc -o hello hello.c
hello.c:2:19: error: stdio.h: No such file or directory
hello.c: In function ‘main’:
hello.c:4: warning: incompatible implicit declaration of built-in function ‘printf’
sleipnir:~ gt$ gcc --sysroot /Developer/SDKs/MacOSX10.6.sdk  -o hello hello.c
sleipnir:~ gt$ 

Simple Encryption Library for QT (improved)

Update 2022-08-12: It turned out that the library (v1.0.0) did not build with QT 5 because of depricated QT APIs. There is now a new version below (v1.0.2) that should work on QT5 (and hopefully QT6). The randomness setting the Initatialization Vector is much improved and at least in theory this was a weak part of v1.0.0. There was also a function “toAscii” that was deprecated and I replaced it with “toLatin1”, so anyone using the command line tool should check that the same passwords work after upgrading to 1.0.2.

A while ago I posted a simple encryption library for QT on this blog. I have now made some improvements and publish a new version. Major improvements are:

  1. Improved performance
  2. Added non patented Serpent Algorithm
    (easy to include and build without RC5)

As before, SimpleQtCryptor should work on all QT platforms without modification. It has no dependencies to anything outside QT and just uses qt datatypes.

Performance – SimpleQtCryptor vs OpenSSL
Since encryption is just overhead to any program using it performance is important. I have tried to optimize SimpleQtCryptor as much as possible, without making the code hard to read or risking portability.

For practical purposes, its performance is comparable to that of OpenSSL. This is on an Athlon II X2 250 3GHz cpu running Ubuntu:

RC5-32/CBC      RC5-64/CBC      RC5-64/CFB      Serpent/CFB     AES-128-CFB
6.5s / 9.0s     3.5s / 6.1s     3.2s / 5.9s     16.4s / 17.6s   5.8s / 7.8s
6.3s / 9.5s     3.5s / 6.1s     3.1s / 5.7s     16.4s / 19.0s   6.0s / 8.3s

Values are presented as user time/real time (including a sync command).
First line is encrypt, second line is decrypt. The data is a 512MB file.

The first 4 columns are SimpleQtCryptor using different algorithms and modes of operation. The last column is 128-bit AES for OpenSSL.

Performance – different machines
For different machines, benchmarks have been made (just algorithm, no streaming or I/O):

                                RC5-32  RC5-64  Serpent 
Athlon II X2 250 3GHz   | enc   4.6s    2.3s    14.6s   
512Mb data, Ubuntu      | dec   4.6s    2.3s    14.8s
Athlon II X2 250 3GHz   | enc   5.8s    3.2s    22.4s
512Mb data, Windows7 64 | dec   5.6s    3.2s    20.6s
Intel Core i5 2.3GHz    | enc   6.9s    3.4s    19.1s
512Mb data, Mac OS X    | dec   6.6s    3.3s    19.2s
Intel Pentium(M) 2.0Ghz | enc   10.9s   47s     35s
512Mb data, Windows7 32 | dec    9.8s   46s     36s
Intel Atom z520 1.33Ghz | enc   20.2s   83s     113s
512Mb data, Windows7 32 | dec   19.2s   84s     130s
PPC G4 866Mhz           | enc   20.4s   62s     85s
512Mb data, Mac OS X    | dec   32.9s   61s     83s
ARM,QNAP TS109 500Mhz   | enc   8.6s    30.4s   58.4s   
64Mb data, Debian       | dec   8.2s    26.4s   92.7s   

It is fascinating to see how different CPUs perform. A few comments:

  • 32 bit machines suffer more from the 64 bit version of RC5, than the other way around – stay with 32 bit unless you know most clients will be 64 bit
  • Serpent uses a precomputed SBOX table (16kb), and CPUs with little cache (Atom and especially the ARM) underperforms on Serpent
  • The Mac OS X G4 compiler fails to use the assembler right roll used in decryption (but finds left roll for encryption) which makes RC5-32 suffer (but not Serpent, for some reason).
  • See how much slower the program runs on Windows 7 than on Ubuntu (on the Athlon II X2). The Microsoft SDK and Microsoft compiler is used, and I expected it to outperform gcc, not the other way around. I wonder if this applies to 32-bit machines as well, but currently I have no dual boot 32 bit machine available.

As usual, building is easy with QT:

 $ qmake
 $ make

Including in your project
If you want to include the SimpleQtCryptor in your project just copy these three files to your project:

  serpent_sbox.h (not necessary, but improves serpent performance 5-10 times)

You only need to #include simpleqtcryptor.h.

In the beginning of simpleqtcryptor.h there is a #define WITHRC5 that you can remove if you do not want RC5 in your program (for legal reasons).

The README file should tell you most things you need to know to include and use the library.

Bad implementations of encryption algorithms is a very bad idea. I believe my implementation is correct and secure – I can not guarantee it. Implementation details (especially regarding modes of operations) make this library incompatible with other encryption libraries. You can not (expect to) decrypt data with any other implementation, even if they use the same encryption algorithms.

The source code for SimpleQtCryptor is here released under the GPLv3 license. If you need another license for the (not patent encumbered) Serpent part I will try to be flexible.

The implementation of Serpent was originally coded in 2000, before the AES competition was resolved. Later Serpent lost to Rijndael, which became AES. In 2011 this Serpent implementation was ported to QT and optimized.

The implementation of RC5 was made in 2010 because I wanted simple encryption for QT, without being dependent on any non-qt-components. RC5 was chosen (despite it is patent protected) because it is a very simple algorithm to implement.

The command line tool
The library comes with a command line tool. The purposes of the command line tool is:

  • To demonstrate how to use the library in QT code
  • To facilitate self-test functionality – you can run this after building on your machine/OS/qt version to ensure compability with other builds.
  • To be used as a benchmark tool

If you want a simple command line encryption tool I strongly recommend you use OpenSSL instead!

This is how to use command line tool:

  SimpleQtCryptor -t testfile
  SimpleQtCryptor -b e|d rc532|rc564|spt Mb (benchmark Mb)
  SimpleQtCryptor -e OPTIONS
  SimpleQtCryptor -d OPTIONS
  SimpleQtCryptor -h
  -k SecretFile (preferred to -p)
  -p Secret (default = )
  -i IndataFile
  -o OutdataFile
  -rc5    : use native RC5 algorithm (default)
  -rc532  : use 32-bit RC5
  -rc564  : use 64-bit RC5
  -spt    : use Serpent algorithm
  -cbc    : CBC
  -cfb    : CFB (default)
  -n      : no header
  -v      : verbose

Download (latest 1.0.2) (updated 2022-08-12)
Source code: SimpleQtCryptor-1.0.2.tar.xz
I dont really see that I would build the command line tool and distribute binaries for any platform.

Download (old 1.0.0)
Source code: SimpleQtCryptor-1.0.0.tgz
Command line tool for Windows: SimpleQtCryptor-1.0.0-x86.exe, SimpleQtCryptor-1.0.0-x64.exe

At this point I don’t supply any binaries for Linux or Mac OS X, however a Symbian version should show up some day.