Try Out Your Reversing Skills

[Maddox]

(on topic)
The solution for this is

Code Select Expand


BOOL __fastcall funcc(char *param)
{
   int i = 0, eax = 3, edx;

   while(i < 0x0c)
       eax += (param[i++] - 0x30) ^ (eax + eax);

   edx = (eax % 0x0a) + 0x30;
   
   if(edx == param[0x0c])
       return 1;

   return 0;
}


[iago]

(on topic)
The solution for this is

Code Select Expand


BOOL __fastcall funcc(char *param)
{
   int i = 0, eax = 3, edx;

   while(i < 0x0c)
       eax += (param[i++] - 0x30) ^ (eax + eax);

   edx = (eax % 0x0a) + 0x30;
   
   if(edx == param[0x0c])
       return 1;

   return 0;
}


You do realize that I posted the solution in my initial post in a black quote box?

<edit> and, I like my solution better.  for > while

[Maddox]

Hah, I never noticed that.  

[Mephisto]

The code is very similar to Yobgul's public one, except I changed the initial parsing a little.  The actual running is pretty much the same as his.

Who is YobGuls?  I've never heard of him before until I started coding for Battle.net which has no only been two weeks when I tested out his hashing algorithm and check revision.

[iago]

The code is very similar to Yobgul's public one, except I changed the initial parsing a little.  The actual running is pretty much the same as his.

Who is YobGuls?  I've never heard of him before until I started coding for Battle.net which has no only been two weeks when I tested out his hashing algorithm and check revision.

He's some ancient and powerful person in battle.net's history.

[Maddox]

The only program I ever saw from YobGuls was a stand-alone d2 gamebot that didn't get very far.

[Mephisto]

Is he still around?

[iago]

Probably.  I wouldn't be surprised if he's a member of vL under a different name.  *looks around suspiciously*

[Mephisto]

^^

[Adron]

Probably.  I wouldn't be surprised if he's a member of vL under a different name.  *looks around suspiciously*

I don't know, but I don't think so. He was clever and good at reversing, but he wrote simple code. He didn't refine it as much as we did. He renewed bot making by being the first person to widely publicly post the results of his reversing. As far as I know, he dove into it for a limited time and then got bored. I think he was more skilled as a hacker/reverser than as a programmer.

[Death_Ryder]

By the way, I noticed a little problem with your original asm code:

Code Select Expand


--snip--
   mov     eax, 1  
   retn    8
bottom:
   xor     eax, eax
   retn    8


Isn't it a tad unusual for a __fastcall function with only 1 param to be returning 8 bytes to the stack?

~Death_Ryder

[iago]

I think there was a second parameter, but it was irrelevant for that.

[TheMinistered]

I thought fastcall didn't even use the stack. I thought it used registers for passing arguements to functions.  I could be wrong and correct me if I am.

[iago]

The first 2 parameters are ecx/edx, after that they are done like stdcall.

[Maddox]

The first 2 parameters are ecx/edx, after that they are done like stdcall.

In your previous post you meant to say "third."