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tim6389 · Professional Member Joined: 01 Aug 2002 Posts: 790

hello all (yes i'am still around)

hi all long time no talk Smile

yes its me!!! question to ask -

maybe i don't understand the checksum like i thought i did Sad

here is what i'am doing.

it i make a exe then uses a packer on the exe THEN i check the checksum lets say it saids 875092988 now if i go back to my source code and edit my checksum varible to this 875092988 then re-compile and repack it.. this should pass the checksum right???? well it don't why? what i'am doing wrong?

thanks

p.s i hope i explain this well

Serge · Posted: Mon Jan 12, 2004 8:35 am Post subject:

hi tim,

i'm not sure about this but i suspect that the checksum of a file is determined by its contents...hence changing an "a" to a "b" in a file could change its checksum

perhaps a google search will help or someone more knowledgeable

serge

tim6389 · Professional Member Joined: 01 Aug 2002 Posts: 790

what you say does make sence Sad

also to i can't even have it check file size cuase the packer packs it diff each time you run it (even tho i have the same compress rate set the same every time) some times when i pack it it will make file size 22,180 then next time it makes it 22,280 bytes Sad

grrrrrrr there has to be a way to do this...

well i will do some checking on the net , if any of ya have any ideas please post

thanks

Vic D'Elfant · Posted: Mon Jan 12, 2004 9:05 am Post subject:

You could use a ini file to store the checksum of you program (encrypted, if you want), and then let your program compare the saved checksum in the ini file to his own.

This way, the checksum doesn't change when you save it to the inifile Smile

Regards,
Vic

Skit3000 · Posted: Mon Jan 12, 2004 3:20 pm Post subject:

Or, if you can, make a little DLL which can be called from your program. That way, you only have to change the checksum in the DLL if you re-compile your program. You can also let it check other things like size, creation date, etc... Smile

tim6389 · Professional Member Joined: 01 Aug 2002 Posts: 790

the ini file is one thing i was things about last night and for a dll that is other good idea...hummm

i will play with some ideas

thanks all

vdsalchemist · Posted: Mon Jan 12, 2004 5:33 pm Post subject:

Hi Tim,
There is already a DLL that can do checksums on a file. Take a look at my Guardian.dll it can do either a standard checksum or an encrypted checksum. You can get the DLL as part of my Gadget download.

tim6389 · Professional Member Joined: 01 Aug 2002 Posts: 790

mindpower - thanks will check it out but the problem i'am having is not how to do a checksum it is how to store it WITHOUT using a ini file. but for the way it looks i will have to uses a ini file Sad

thanks

Hortalonus · Posted: Mon Jan 12, 2004 7:19 pm Post subject: Re: ok

FreezingFire · **Admin Team** Joined: 23 Jun 2002 Posts: 3508

The VDSDLL3's VDSMD5.DLL can calculate the MD5 checksum of a file.

tim6389 · Professional Member Joined: 01 Aug 2002 Posts: 790

registry - would work to but i was hoping to keep it within the exe but i know that this can't be done Sad

FreezingFire · **Admin Team** Joined: 23 Jun 2002 Posts: 3508

You could append it to the end of the executable file Smile

tim6389 · Professional Member Joined: 01 Aug 2002 Posts: 790

yup i was thinking the same thing Smile

hehehe well thanks all i have a few ideas to try Smile

Skit3000 · Posted: Tue Jan 13, 2004 2:25 pm Post subject:

Please note that if you append it to the of the exe file, you have to remove it right after loading, so that the checksum is right. If you don't remove it, the checksum probably will give another value... Sad

tim6389 · Professional Member Joined: 01 Aug 2002 Posts: 790

Skit3000 - you have a good piont there. i would like to know is how they do it in diff programming like vb,c+ cuase you would think they would have the same problem i'am having. without having to uses a ini file.

like i say before i can't even have it check file size cuase when you pack it. its diff every time Sad