[Idea] Disable the CRC

LemoniscooL · 09/27/2009, 22:22

Hey there i looked around in the Dragonica files a bit and in the Gameguard folder located in the Release folder there is an .ini file named DragonicaEU.ini
After decrypting it i could see the following lines in there:

Code:

[GAMEMON]
GAME_NAME=DragonicaEU
UPDATE_SERVER=patch.gameguard.gpotato.eu
UPDATE_PATH=/DragonicaEU/RealServer/
BACKUP_SERVER=
BACKUP_PATH=
OPTION_VALUE=0
SPEEDCHECK_INTERVAL=1000
[B]USE_GGSCAN=1[/B]
[B]GAMECRC=2[/B]
SENDERRLOG=3
LOG_SERVER=211.233.43.45
TACHYON_PAYURL=http://www.bitdefender.com/media/html/en/inca-2009/

the bold lines got my attention first so i googled around a bit and as i thought the "GAMECRC=2" indicates if the Game files are CRC checked
to turn it of it has to be "GAMECRC=0"
the only problem is.. the file has to be encrypted again and i couldnt find any tool for that does anyone know a tool for it or a way to encrypt it again?

i attached the tool i used to decrypt the file
it is not made by me but i dunno who gets credits for it xD google gave it to me ^^

greetz

chuj761 · 09/27/2009, 23:00

Unfortunately there is no way to encrypt the files.Plain and simple.

LemoniscooL · 09/27/2009, 23:06

as far as i know the files are encrypted using RSA cryptography
Transleted from wikipedia:

Quote:

RSA uses a keypair: a private key thats used to decrypt the files, and a puplic key used to encrypt the files. the private key is normally kept secret and can not, or only with massive work, be calculated from the puplic key.

that means we ned the so called puplic key and a tool for RSA encryption to encrypt the files

alexis62 · 09/27/2009, 23:08

Quote:

Originally Posted by eMale

the bold lines got my attention first so i googled around a bit and as i thought the "GAMECRC=2" indicates if the Game files are CRC checked
to turn it of it has to be "GAMECRC=0"

If this really works, you think that DSEE and company work again? Or will it simply a new remake?

In short, I did my survey =) You have my support = D

LemoniscooL · 09/27/2009, 23:14

hehe this would get "DSEE and company" to work again i think cuz everyone complained about the CRC .. this would disable the CRC ^^

i read a lot about encrypting those files but every post refers to a post on the cheat engine forum and those posts were deleted there -.-

Zacko7 · 09/27/2009, 23:28

Very nice find. We would need the original encrypter that they used to encrypt the game, and hopefully there is not a checksum that we need to correct as well. Still have a ways of work to do, but this is a great find.

alexis62 · 09/28/2009, 00:09

When I change the value "GAMECRC = 2" in "GAMECRC = 0" (gPotato.eu \ Dragonica \ Release \ GameGuard), it is automatically updated to launch the game and become again the value "GAMECRC = 2" -__- '

When I try to edit files: DRAGONICAEU.INI & Dragonica.ini (gPotato.eu \ Dragonica \ Release) so that the change does not occur, the game starts over and GameGuard seeks re-install = S

LemoniscooL · 09/28/2009, 00:16

that may be cuz the file isnt encrypted and game guard thinks hmm its damaged .. re install please ^^

Snuggleopolis · 09/28/2009, 00:38

It's a good idea in theory but here are the problems with it.

1. No way to encrypt the files.
2. HackShield isn't that stupid.
3. There are checks to make sure people haven't done this.

They have checks to make sure ggcrcscan is active. You have to totally go through the code to find the checks and make them think that it is actually active. It's a lot more complicated than changing 2 to 0.

LemoniscooL · 09/28/2009, 00:54

it is not HackShield .. its GameGuard .. hackshield can be totally turned of in minutes, gameguard not thats a difference =P

this is the first time im trying to do something with gameguard, i dun know much about gameguard and this is just a try, if it fails .. hm well, ill try another thing ^^

and .. there HAS to be a way to encrypt the files .. cuz when we get them, they ARE encrypted and we can decrypt them ..

alexis62 · 09/28/2009, 02:33

Exactly, GameGuard is deemed to be easily circumvented x)

r3dbull88 · 09/28/2009, 07:58

Quote:

Originally Posted by eMale

it is not HackShield .. its GameGuard .. hackshield can be totally turned of in minutes, gameguard not thats a difference =P

this is the first time im trying to do something with gameguard, i dun know much about gameguard and this is just a try, if it fails .. hm well, ill try another thing ^^

and .. there HAS to be a way to encrypt the files .. cuz when we get them, they ARE encrypted and we can decrypt them ..

What key does the "decrypt tool" uses to decrypt? (check on tool mader website/forum/etc..)

Once you have decrypted / modified and re-encrypt you need to make sure that GG (aka GameGuard) either doesn't check that file or doesn't update it, which is kinda harder than the first part, since if you find a way to manipulate GameGuard you could just de-activate or run a previous version of it.

hsyeow · 09/28/2009, 08:58

Quote:

Originally Posted by eMale

as far as i know the files are encrypted using RSA cryptography
Transleted from wikipedia:

that means we ned the so called puplic key and a tool for RSA encryption to encrypt the files

Even though Wiki's explanation is technically correct, this is not true here. You do not distribute private key, only the public key. What HackShield has is the public key for decryption and what you need is the private key to encrypt the file back.

Quote:

Originally Posted by r3dbull88

What key does the "decrypt tool" uses to decrypt? (check on tool mader website/forum/etc..)

Once you have decrypted / modified and re-encrypt you need to make sure that GG (aka GameGuard) either doesn't check that file or doesn't update it, which is kinda harder than the first part, since if you find a way to manipulate GameGuard you could just de-activate or run a previous version of it.

GG probably check local files' CRC/MD5 checksum against the one in the update server. Any disparity and it'll use the one in the server.

micecats · 09/28/2009, 10:35

Won't work, inca use a private key to encrypt their ini files, you can decrypt files, but you can't encrypt them back...has been proved many times in the past.

The only 2 ways to bypass CRC :

1. Hook GG, get Dragonica handle, and telling GG to make a fake driver file by finding the ReadProcessMemory location.

2. Easier, codecave your hacks, and use EIP register to jmp to your codecaved addresses. (problem is you can only 3 registers.)

LemoniscooL · 09/28/2009, 13:08

okay keep cool ^^ this was just an idea and as i said this is the first time i try things for gameguard .. till now i only made things for hackshield and xtrap those are way easier xD