Slf modifyinf code or by Anasazi

/*
   This code was written and tested using Windows XP, SP2 running inside VirtualBox.
   Visual C++ 6.0
*/

#include <stdio.h>
#include <stdlib.h>
#include <windows.h>

// Beginning of printfFunction
void printfFunction(char *szText){
 printf("%s\n", szText);
}
// Marks the end of printfFunction
void printfFunctionStub(){}

void enc(DWORD dwAddress, DWORD dwSize){
 __asm{
  mov ecx,dwAddress
  add ecx,dwSize
  mov eax,dwAddress
  C_loop:
  xor byte ptr ds:[eax],0x5A
  inc eax
  cmp eax,ecx
  jl C_loop;
 }
}

int main(){
 DWORD dwPrintFunctionSize = 0, dwOldProtect;
 char *fA = NULL, *fB = NULL;

 // Obtain the addresses for the functions so we can calculate size.
 fA = (char *)&printfFunction;
 fB = (char *)&printfFunctionStub;

 // Get total function size
 dwPrintFunctionSize = (fB - fA);
 
 // Test the function
 printfFunction("Hello A!\n");
 
 // We need to give ourselves access to modifify data at the given address
 VirtualProtect(fA, dwPrintFunctionSize, PAGE_READWRITE, &dwOldProtect);
 
 enc(fA, dwPrintFunctionSize); // XOR encrypt the function
 enc(fA, dwPrintFunctionSize); // XOR decrypt the function
 
 // Restore the old protection
 VirtualProtect(fA, dwPrintFunctionSize, dwOldProtect, NULL);

 // Test the function
 printfFunction("Hello C!\n");

 return 0;
}