The problem is not simple experiment it ---

  First, open the View:

Requirements subject is to find a user named hello registration code, RI initial guess is, we simply registered it and see.

User name is hello whatever you enter a registration code, the result is not unexpected invalid, from here we can see here the emergence of a new MessageBox , with an initial guess ollydbg debugging time will be used here to guess the final flag is registered code

 

Then still the same first check a shell, you can see there is no shell

 

Try ida open look, the Shift + F12 look

 

Here you can see very obvious tips, keys right and wrong, continue to go on with the View

 

Here you can see whether it is right or wrong will pop MessageBoxA after the above should be that we enter the registration code error message box pops up, we continue to look to see the push offset Caption; " message "   Not surprisingly, the information presented here should be the input of the . Continue to analyze

 

The structure was simply input information to confirm, then pop a MessageBox , see what did not see, and then use ollydbg look

 

 

Double-click to enter discovered the key point here should be the key to jump up

 

Continue to see

 

 

He seemed to see what Happy @ Here is what should be returned to the ida look

 

Check this function

 

把每个字符的序号(从 0 开始算)与这个字符的ASCII码的平方相乘 , 然后整体再加上序号 , 得到的和继续对 0x42 求余 , 最后将结果加上 33 , 然后再转为ASCII码

 

 

不难，一开始以为用od就可以了，最后还是用的ida看一下。。。。。。挺chun的