September 2008 - Posts

• Minimize the size of your program - low level

  NOTICE: The following is not intended for real-world application. It is just an intellectual exercise to minimize the size of the program. The generated PE file may or may not be valid as it depends on behavior of specific architecture, OS and toolset. Read More... Posted Saturday, September 27, 2008 4:37 PM by xiangfan | 1 Comments

• Minimize the size of your program - assembly source

  ; based on tiny.asm, modified by xiangfan ;e_cblp 2b ;tbl 1b ;hexstr 1b ;LoaderFlags 4b BITS 32 ; ; MZ header ; ; The only two fields that matter are e_magic and e_lfanew mzhdr: dw "MZ" ; e_magic dw 0 ; e_cblp UNUSED ; ; PE signature ; pesig: dd "PE" Read More... Posted Saturday, September 27, 2008 4:34 PM by xiangfan | 1 Comments

• Minimize the size of your program - high level

  NOTICE: The following is not intended for real-world application. It is just an intellectual exercise to minimize the size of the program. The generated PE file may or may not be valid as it depends on behavior of specific architecture, OS and toolset. Read More... Posted Friday, September 19, 2008 1:46 PM by xiangfan | 1 Comments

• Obfuscate your code

  Obfuscation is widely used to protect your code from reverse engineering. Here is one example which takes advantage of indirected call and opcode overlap in X86: __declspec ( naked ) void Fun1() { __asm { //obfuscation chunk call LABEL1 LABEL1: pop eax Read More... Posted Tuesday, September 16, 2008 11:49 PM by xiangfan | 1 Comments Filed under: C++, Reverse Engineering

• Play with the C++ compiler - compile nightmare

  Playing with the compiler is interesting. One challenge for the compiler writer is compilation performance. There're many kinds of C++ code which are the nightmare for the compiler. Now let's go! 1. Preprocess a. Self Inclusion (GCC only) Normally, the Read More... Posted Monday, September 15, 2008 3:49 PM by xiangfan | 1 Comments Filed under: C++, VC, Bug, GCC

• Magic behind ValueType.Equals

  In "Effective C#", Bill Wagner says "Always create an override of ValueType.Equals() whenever you create a value type". His main consideration is the performance, because reflection is needed to compare two value types memberwisely. In fact, the framework Read More... Posted Monday, September 01, 2008 4:35 PM by xiangfan | 1 Comments Filed under: Optimization, Bug, C#