Month: May 2011

Two hashes collide

Normally MD5 is used to validate many files at Internet for its integrity, but few people know bad guys could force a malicious file to have same MD5 signature like original one.

If you want to know more about it I suggest you read this web page:

Alternativa ao Skype

Agora que a Microsoft comprou a Skype não demora muito até o suporte para Linux deixar de existir. Não estou sendo pessimista, mas conheço as práticas sujas desta empresa há mais de 15 anos.

Há aproximadamente cinco anos eu usava um programa chamado WengoPhone que era uma alternativa open-source ao Skype. Mas o software mudou de nome e agora chama-se QuteCom e pode ser instalado com um simples comando:

$ sudo apt-get install qutecom

Mais informações acesse:

Android Compatibility

If you developed a device powered by Android and you want to add it to Android Market, then read this page:

Basically you should follow these steps:
1) Obtain the Android software source code. This is the source code for the Android platform, that you port to your hardware.

2) Comply with Android Compatibility Definition Document (CDD). The CDD enumerates the software and hardware requirements of a compatible Android device.

3) Pass the Compatibility Test Suite (CTS). You can use the CTS (included in the Android source code) as an ongoing aid to compatibility during the development process.

You could download the Compatibility Definition from here:

Finally you could contact Android Compatibility from here:

Share your invention

“As we enjoy great advantages from inventions of others, we should be glad of an opportunity to serve others by any invention of ours; and this we should do freely and generously.”

— Benjamin Franklin

Undestanding Microsoft Word 4 binary format and early versions

Today reading Harald Welte’s blog I discovered here is creating a script to extract ASN1 definition from GSM documentation written on MSWord4.

Then he discovered a web site with MS Word 4 binary format specification:

He noticed none MS Word released lasts 10 years could open it. Then I think it could be very interesting adding this support on LibreOffice/OpenOffice.

Evoluir significa perder a essencia?

Hoje descobri que o Linux nao funciona nativamente nos processadores 80386, so funciona se o kernel emular o i486. Esta mudanca ocorreu por volta de 2003/2004 quando houve uma mudanca no GCC que passou a exigir alguns OPCODEs que so’ existiam no 80486 e superior:

Este problema é semelhante ao que ocorre com o Android que só suporta nativamente os processadores ARMv4 ou superior, mesmo o ARMv4T que nao possui os OPCODEs necessarios nao e’ suportado nativamente, felizmente neste caso alguem tambem fez as modificacoes necessarias para funcionar:

Realmente e’ um pouco triste ver estas coisas acontecerem. Mas faz parte da evolucao do Linux, um dia ele deixaria de suportar o processador que foi usado para traze-lo ao mundo.

How to recover deleted files?

If you deleted some important files in your hard disc or pen-driver then the first step is stopping using it (otherwise its location area could be write). Sometimes even umounting the disc partition could damage your file.

There are many software used for recovery some specific file format, for example Photorec to recover pictures in your Memory Card or hard disc.

But if you want to use a single program where you define which files are you looking for, then scalpel will be the solution for you.

Here you can find an example explaining how to recover PDF files:

Just defile the file type you are willing and go ahead.