Hello can some body tell me what the opposite of AND is for example: magic_value AND c3506f2h == 83004e0h then what is the magic_value and how is the calculation working???? I hope someone can help me with this. thanx
Posted on 2002-05-20 05:15:21 by h0nz1k
Honziku, sorry there is not such a think as opposite to AND,
Think about it as a filter. What you loose you can't get back.

1 AND 1 = 1
1 AND 0 = 0
0 AND 1 = 0
0 AND 0 = 0

Regards:

forge
Posted on 2002-05-20 05:47:30 by forge
Aha.. thanx for the answer so if i'm correct this example is not possible(it's a piece out of a crackme).

xor ebx, 6a451efb
AND ebx, 0c3506f2
cmp ebx, 083004e0
jne 004538c0 (jmp to wrong serial)

because 0 and 2 == 0 ,
but ? and f == e is not posible.

is that right? or am i looking wrong??
Posted on 2002-05-20 06:20:54 by h0nz1k
h0nz1k: Anything related to reverse engineering or cr*cking, even cr*ckmes, is not allowed on this board.

Please read the rules before posting:
http://www.asmcommunity.net/board/announcement.php?forumid=23

Thomas
Posted on 2002-05-20 06:24:15 by Thomas
oke
Posted on 2002-05-20 06:30:45 by h0nz1k

h0nz1k: Anything related to reverse engineering or cr*cking, even cr*ckmes, is not allowed on this board.

Please read the rules before posting:
http://www.asmcommunity.net/board/announcement.php?forumid=23

Thomas


Actually, the rules (as they appear from above link) do not state that anything RELATED to reverse engineering is off limits for this site. They read:
There will be no linking to any cracking, warez, virii or reverse-engineering site

and a bit before that:
There will be no crackz (i.e. programs that alter another program with the sole purpose to defeat its protection scheme allowing for unauthorized usage) allowed.

Neither place mentions cr*ckme's, which in fact rather seem to fall outside the rules. The point is ofcourse that it's not illegal to reverse a crackme.
Anywho, I guess that either the rules should state that ALL subjects of reverse engineering and cr*cking are forbidden, or that there is a fine line between legit and illegit subjects for this board, depending on what the mods see fit for the board. Just figure the rules might need a bit of clarification on this point.

Fake
Posted on 2002-05-20 06:40:54 by Fake51
Fake51: Okay, Hiroshimator could add a specific rule for these situations but from the other rules you might have guessed these topics aren't allowed.

The point is ofcourse that it's not illegal to reverse a crackme.


We've had numerous discussions about what's legal and what's not, but as Hiroshimator is responsable for everything people write here, he's the one to decide. He has decided wisely not to allow these kind of things, no matter what you think of it.

Thomas
Posted on 2002-05-20 06:51:37 by Thomas

Fake51: Okay, Hiroshimator could add a specific rule for these situations but from the other rules you might have guessed these topics aren't allowed.

Actualy, what I guessed from those topics was that anything illegal per se is banned on the board (which makes perfectly good sense). I'm not arguing as to whether or not these subjects should be on the board or not, just pointing out that the rules stated elsewhere are somewhat ambiguous regarding the subject of legally reverse engineering code (note: if all reverse engineering is banned on the board, all posts regarding the inner workings of OS' would have to be deleted as well, since they are in fact tokens of reverse engineering. These are allowed though).


We've had numerous discussions about what's legal and what's not, but as Hiroshimator is responsable for everything people write here, he's the one to decide. He has decided wisely not to allow these kind of things, no matter what you think of it.

Thomas


Basically my point: the mods should have a ruling on subjects not specifically mentioned in the rules, and then modify the rules accordingly, if the issue is of some importance (seeing that ppl keep coming here asking both legit and illegit questions, the rules may need to be stated a bit more clearly). I wasn't aware that Hiro had decided thus; had I been, then obviously I wouldn't have posted.

Regards
Fake
Posted on 2002-05-20 07:01:35 by Fake51
(note: if all reverse engineering is banned on the board, all posts regarding the inner workings of OS' would have to be deleted as well, since they are in fact tokens of reverse engineering. These are allowed though).


Information about the inner workings of the OS do not directly associate this board with reverse engineering, it depends on the nature of the information. The rules are to keep "hey i need to know how this prog works can u help me reverse it"-questions out of here.

Basically my point: the mods should have a ruling on subjects not specifically mentioned in the rules, and then modify the rules accordingly, if the issue is of some importance (seeing that ppl keep coming here asking both legit and illegit questions, the rules may need to be stated a bit more clearly). I wasn't aware that Hiro had decided thus; had I been, then obviously I wouldn't have posted.


I understand your point, I'll ask Hiro if he thinks the rules need to be clearified.

Thomas
Posted on 2002-05-20 07:30:25 by Thomas



Information about the inner workings of the OS do not directly associate this board with reverse engineering, it depends on the nature of the information. The rules are to keep "hey i need to know how this prog works can u help me reverse it"-questions out of here.



I understand your point, I'll ask Hiro if he thinks the rules need to be clearified.

Thomas


Cheers
Fake
Posted on 2002-05-20 07:47:04 by Fake51
the rules have been updated. Is this more clear?

About the inner workings of an OS :/ we try to balance the thin line between love & hate. None of us wish to provide crackers a haven nor deprive all of us of useful info with a legitimate purpose (like such info that Matt Pietrek posts in MSDN journal).

The fact in the matter is however that recently laws have become more stern and this server is located in the states, so one has to be double careful with those new anti-terrorist acts.
Posted on 2002-05-20 08:04:05 by Hiroshimator
This is a basic logical (or should that be bitwise :grin: ?) premise of programming.
The principal of bitwise operations are fairly fundamental to programming in assembly, and not understanding them shows you probably aren't really ready for the more complex tasks.

Take the number 0FFFFh:
0FFFFh = 0000 0000 0000 0000 1111 1111 1111 1111b
0FFFFh AND 01234567h == 5678h because:
0000 0000 0000 0000 1111 1111 1111 1111b
0000 0001 0010 0011 0100 0101 0110 0111b -- AND
0000 0000 0000 0000 0100 0101 0110 0111b
(Use the true table above in forge's post).

Hence we have the following:
33333333h AND 01234567h == 01230123h
0011 0011 0011 0011 0011 0011 0011 0011b
0000 0001 0010 0011 0100 0101 0110 0111b -- AND
0000 0001 0010 0011 0000 0001 0010 0011b

Mirno
Posted on 2002-05-20 08:50:38 by Mirno

the rules have been updated. Is this more clear?

About the inner workings of an OS :/ we try to balance the thin line between love & hate. None of us wish to provide crackers a haven nor deprive all of us of useful info with a legitimate purpose (like such info that Matt Pietrek posts in MSDN journal).

The fact in the matter is however that recently laws have become more stern and this server is located in the states, so one has to be double careful with those new anti-terrorist acts.


Nice and clear.

Regards
Fake

Note: The interesting thing bout all of this is that the first post by honzik was fine and acceptable, but the second one altered it, due to the mention of what she/he is working with. Had she/he sticked to the first post, or just included the small piece of code without mentioning sn's, it would have been just another post regarding some basic knowledge. Just goes to show exactly how thin the line is between sharing useful info and helping crackers, as Hiro pointed out.

Note on personal interest: don't take these posts as an indication that I think board policy is wrong. I agree with Hiro on the policy of the board.
Posted on 2002-05-20 09:04:59 by Fake51
Note: The interesting thing bout all of this is that the first post by honzik was fine and acceptable, but the second one altered it, due to the mention of what she/he is working with. Had she/he sticked to the first post, or just included the small piece of code without mentioning sn's, it would have been just another post regarding some basic knowledge. Just goes to show exactly how thin the line is between sharing useful info and helping crackers, as Hiro pointed out.


Yes if he hadn't mentioned it nothing would be wrong and the question would be answered like any question. There's nothing wrong with this as this won't link the board with illegal activities. However as soon as the person mentions his intent, this link appears and that's exactly what we don't want. People asking about CreateFile could be using it for illegal intent as well. We can't ask about the intent everytime someone posts. There are some topics/posts that suggest illegal intent though (like disassembly listings), in those cases a moderator will jump in and ask about it.

Thomas
Posted on 2002-05-20 09:22:10 by Thomas