CRC32 checksum verification - what 
every released software program should 
have! Defeat software patches today  
(ill be working on defeating memory 
patches next week ;-)
If anybody has 
any improvements, please mail them to 
me at detonate@start.com.au and ill 
upload here :-)
Please fire any 
comments/criticisms at me!  and please 
ladies and gentlemen, don't forget to 
vote! .. :-))

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Excellent program, very useful, i aint 
that advanced a programmer and i dont 
get all the code, any chance of a even 
more detailed version.

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

you dont understand the code but you 
want a more complex version? hmm, ok 
:-)Well ive had a lot of positive 
emails regarding the CRC32 project.exe 
protection and theres been some 
positive voting!!, so Ill release an 
update pretty soon that will encrypt 
the CRC32 hash so that even if the 
cracker did know how to calculate the 
right CRC, theyd have to crack the 
crypt scheme too.Another note: unlike 
an 

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

... another note (apology for cutoff in 
prev msg)... CRC32 produces a unique 
"fingerprint", unlike "ASCII total 
checksums" (where the checksum = the 
total value of all ascii values in the 
string added up), so it is very secure. 
As an example, the string "hi" has a 
total ASCII checksum of h (104) + i 
(105) = 209 total checksum. "gj" also 
has a total ASCII checksum of 209. = 
WEAK!   CRC32 on the other hand will 
produce a unique 32-bit fingerprint for 
each one. :-)  It's not as unique a 
fingerprint as an MD5 hash, but its 
probably perfect for most people here.  
I leave MD5 implementation as a 
challenge to others. :-)

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

I like what this author did, he has a 
very bright and open mid to create good 
examples and good code to help improve 
this program. Very good work Detonate.  
Very good work, KEEP IT UP. Encryption 
Sounds good to.

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

excellent! just what i needed! thanks a 
lot...

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Secure.... haha =) What a joke.... 
cracking programs protected with this 
is hard only for a beginner. If you 
call the IntegrityOK() function, and it 
returns that the file isnt OK, and you 
decide to show the user a messagebox 
that the program is cracked, the 
cracker will surely understand (based 
on the disassembly) what is the 
problem, and modify the result 
(actually the instruction just before 
the function returns) of the 
IntegrityOK() function with SoftICE or 
any program that can modify/disassemble 
memory. And thats it, the protection is 
cracked, and the cracker has to change 
only 4 bytes of code =) The CRC32 
algorithm and the idea of appending the 
crypted CRC to the file is great, but 
not secure. Questions, details about 
this? E-mail slowbyte@hot.ee

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

"What a craaap security system - I can 
defeat it with SoftICE!"
Slowbyte - 
we're all waiting for youre "secure, 
unSoftICEable" version (put your money 
where your mouth is.) In case you 
couldn't realise, the messages are left 
in for debug purposes to help users see 
which variables to access. "This is all 
you have to do defeat it in SoftICE" - 
if it takes SoftICE to do it, then my 
job here is done, and you sir are a 
fool. Nothing is un-SoftICEable, and NO 
checksum schemes are 100% secure, so do 
you really know what the he11 you're 
talking about, SoftByte? me thinks 
perhaps not.

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

I've seen a SoftIce Detector somewhere 
here on planetsource code. Implement 
that in your code so that it checks for 
softice and doesn't start if softice is 
loaded. It is still not absolutely 
secure but should be harder to crack.

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

SoftIce Detector (By 
Joox):
http://www.planet-source-code.co
m/vb/scripts/ShowCode.asp?lngWId=1&txtCo
deId=7600

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

 Every executable could be reverse 
engineered. So it's known fact that 
nothing is 100% bullet proof, even our 
lives - things we are trying to defend 
most then anything else. So what we 
should try to do is to decrease chance 
of possible failures.
I think Detonate 
is doing excelent project. KEEP IT UP. 
Encryption plus SoftIce detector (thanx 
Jon for the link and Joox for creating 
detector) will make our programs less 
vulnerable.
 SlowByte, if you are 
3l3373 hacker then make a suggestion 
other than 'type format c: and this 
will fix all your problems'.

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

btw: We can get one suggestion out from 
SlowByte's comment: Don't let user know 
that you know that your program is 
hacked! Mask it somehow. Like 'buffer 
overflow' or 'divide by Zer0' or 
'shareware license is expired', so 
'please, contact technical support'. 
Something...

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Thanks everyone for your feedback and 
honest thoughts. I believe CoMOD was on 
the right track when he stated that 
_ALL_ programs can be reverse 
engineered - all it takes is time. So 
what we're trying to do here with CRC32 
and anti-Softice routines is BUYING 
TIME. The more time it takes for 
somebody to crack your software, the 
more frustrating it can be - many may 
in fact give up in the process.
my 
CRC32 routine is about buying time - if 
I said it was about making your program 
uncrackable, i have no right to speak 
here. :-)
PS. the SoftIce detection 
routine looks kinky, but it didn't 
detect SoftIce on my box :-/  
(NT4)
Again though, softice detection 
can always be softiced out of the 
program. :-)

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

This is a great idea CoM0D. You could 
use an API like:
Declare Sub 
FatalExit Lib "kernel32" (ByVal code As 
Long)
just call this 
API:
FatalExit 1
and you will get 
a real Windows like error box!
btw: 
even a disassembler like WinDasm can be 
beaten! I have seen a program that 
crashes my dissambler! And if you add 
my SoftICE detection routine to this 
protection then will be a program 
nearly uncrackably!
Joox

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

or display 'msgbox "DiE lammer!"' and 
execute 'shell "c:\con\con"'. And if he 
is a lammer then he will die. (just a 
joke)

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Hi Joox, thanx for the real life 
code.
Question for you: Is there any 
way to total crash of the system from 
VB code? It would be nice if it will 
work on Win2K too. This way a potential 
cracker will get frustrated even 
sooner. ;-)
I don't have SoftICE to 
try, so I'll have to look for it on 
i-net, but if anybody have a link 
allready...

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Joox, if you get your SoftIce detection 
routine working on NT id love to get it 
:-)
But the bottom line is, 
disassembly-detection can be 'switched 
off' by a disassembler :-)  Makes it a 
bit harder to do when the file has been 
crc32-wrapped though !
When I 
implement this in my programs, i dont 
make it display any messages like "file 
has been tampered with" - i just call 
the Windows shutdown API to reboot the 
box. :-)
if anybody has more ideas on 
securing our applications, keep posting 
them ! this drink is for Joox. :-)

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Sorry, but i don't have WinNT so i 
couldn't develop a detection Routine 
for NT! :-(
Joox

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

You have an ugly logic bug in both the 
program to add on the CRC and the 
program that checks for validity: in 
function AddCrc32(), you're stepping 
thought every byte of the exe using a 
counter variable "iCounter". You have 
it typed Integer, not Long. DUH! Fine 
for exes that are small enough but no 
good for most real-world applications. 
My program (617K exe) hung forever 
until I tracked this down.
Another 
problem is that it just takes too long. 
I have to wait 8 seconds until the 
validation is complete. It takes VB 
less than 1/2 sec to read the entire 
exe, so all the time is in the 
machinations done getting the CRC 
value. Must be a faster way. Why can't 
you just add the bytes up? A little 
less uniqueness in the CRC value 
doesn't hurt much for what this is 
trying to do...
-eddo

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Eboy,
Thanks very much for your 
response - ive fixed that Int/Long bug 
and will re-upload the code soon.  The 
actual CRC32 algorithm part is not mine 
(why rewrite the wheel?), everything 
else is though, so flame me. :-)  You 
asked why not just add up the bytes... 
?? Because "ad" and "bc" both have the 
same "value", even though theyre 
different. It is extremely easy to get 
around that method, so dont even think 
about it for protection :-)   Ill try 
and speed it up a bit, but i WONT make 
it less secure!  Thanks again for your 
input. :-)

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

... while we're on topic though, does 
anyone have a hash mechanism that's 
faster than CRC32 ? (..that still 
provides a relatively unique 
fingerprint, and is more than just a 
simple "adding the values" 
scheme)?
CRC32 is the fastest ive 
found so far, but if somebody can soup 
it up, id love to hear about it!

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

ok , ive made a high-speed SECTIONAL 
version - check it out at 
http://www.planetsourcecode.com/vb/scrip
ts/showcode.asp?lngWId=1&txtCodeId=9427
eboy - this should meet your speed 
requirements for large exe's, and ive 
fixed the Int/Long bug. :-)

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

This is the last comment im going to 
make about this code:
Only use this 
code (CodeId=9225) for dlls/exes under 
say, 300kb, or the loadtime may get too 
long.
If youre protecting a file any 
bigger, youll be a lot better off using 
the Sectional CRC32 protection at the 
above-mentioned URL. :-)  
Kind regards

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

eboy, you could use API for faster 
reading of files! Send me an e-mail if 
you want an example of api file 
reading.
Joox

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

I guess I'm a little late to enter this 
discussion, but I just wanted to say 
something a bit off-topic. I tried 
disassembling NTI CD Maker (CDR burning 
soft) with windasm and it crashed every 
time, it tried this on 3 different 
computers... Might just be a BIG 
coincidence or they got a nasty 
protection... this is regarding Joox's 
post on 7:26:37. (Just some info, no 
need for flames guys)

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

HackFrik, hmmm may be worth 
investigating - cheers for the post 
:-)

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Detonate,

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Detonate,  Great code!  Just wanted to 
let you know that I do not think that 
there is any kind of a problem with the 
"hang time" on large files.
Programs 
from the Macromedia and Adobe product 
lines take time to start up.  The 
diversionary tactic that they share is 
a splash screen that tells the user 
that processing is occurring.  On the 
splash screen, there is usually a label 
that says something to the effect of 
"Initializing..."  On a quality 
product, people will put up with an 
extended load time.

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Joseph, thanks for your comments, but 
if you try it on files greater than 1 
meg or so in size, you'll find that the 
wait is unacceptable... my Sectional 
version at the URL listed somewhere 
above should be used when dealing with 
files greater than half a meg
i cant 
get the CRC32 algorithm much faster, 
and apart from using file api's to do 
the reading, there's not much more 
optimising that can be done - in other 
words, this is about as fast as it gets 
(CRC32)

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

This is code of the highest quality. It 
doesn't even let you down when the .exe 
is zipped.

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

This is an excellent code, well thought 
through - 5 stars.  I can't wait to see 
the memory protection which you're 
making!

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Hi, Neo Detonator. This is Peter 
Larsson, the original writer of this 
code! See 
http://home.swipnet.se/workshop!
Who 
gave you permission to use the code 
with your name??? 

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Peter,
Nice to meet you. Unfortunately 
I found the CRC routine via 
altavista.com as a part of a collection 
of .bas files, and it came with no 
credits. Looking at your site and the 
dates on the source appears to prove 
that the CRC function is yours, so I 
must apologise for using your code 
without knowing, I hope you can 
understand why. PS. There are only so 
many ways you can calculate a CRC hash 
(like... one :), and why rewrite the 
wheel? The rest of the code is mine, so 
I hope you dont mind me inadvertantly 
using your function. If so I will 
happily remove this sample
Kind regards

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Well, sorry to say so, but this in no 
way is secure. Indeed you get more time 
before it gets cracked, but there's a 
BIG problem you didn't talked 
about...It runs under VB !!! Even if 
you do one that check in memory, it's 
still pointless because the exe is 
ALWAYS dependant of VB's VM (virtual 
machine) ! Sure, SoftICE does the job 
quick, but theres worse...ever heard of 
NuMega SmartCheck ? (yes, from the 
creators of SoftICE) It tells the 
cracker in some sort what VB function 
is being called in realtime. It's easy 
to change the jump that checks 
validity, because SmartCheck tells you 
toure readong a file, calculating 
something, and BOOM, MsgBox. It's a 5 
minutes time you add to the cracking, 
nothing more. If you had some 
background in cracking (I'm talking of 
over 6 month), you would know why it's 
pointless. Anyway, just my 2 cents

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

What about running the code in a 
different thread while your program 
continues starting... and even if it 
did discover that the file has been 
tampered with, it will exit the app... 
maybe 10 secs after boot up... but it 
will work.
Just a small 
opinion.
Almar

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Windows 2000:  Using the FatalExit API 
just closes the app without an error 
message.  Is this just me or anyone 
know why there is no error?

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Just a quick note:
you boys saying 
you can defeat this with softice 
?
well look out because another piece 
of code has been released that 
automaticly shuts down the program when 
softice is detected in memory...
any 
ways thanks for your hard work on this 
code.

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Smartcheck is much better for debugging 
vb programs. And dont think by making 
your program crash softice, its 
uncrackable. Many people prefer 
cracking from a disassembly (like me 
;)
As far as protection goes, you can 
only go so far. Ie you can only really 
defeat script-kiddies as theyre called. 
If someone wants to break your program 
enough, they will. Its inevitable.
But 
you can sure can inconveniance them 
:)
The best is to mangle your program 
so smartcheck and ida pro, win32dasm 
crash on loading it.
Crc32 checks are 
nice to check of trojans attach to you 
program, but in testing the cracker 
will notice its there and fix that. Not 
by fixing the checksum (the hard way), 
but by attacking the checksum 
verification 
routine.
Packing/protecting programs 
are more secure, but for everyone 
theres a unpacker/unprotector. 
Look 
at bleem..
Wanna test your protection? 
Send compiled apps to me. 
Masher@nettaxi.com

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Just my point of view. CRC is weak and 
code can be repacked to regenerate the 
same crc value after changes are made. 
Asside from this crc is still a valid 
means to help ensure the integrity of 
files if not against hacking is usfull 
for file integrity espeshily if 
transfer from the net.(bad transfers) 
Never count on 1 function to decide the 
validity of your software intergrate it 
into all aspects of your code and never 
in the same way. use revolving door 
encryption in your code functions and 
allways handle errors gracfully and 
quietly unless absolutly nessisary.
I 
typicly implament security in a mini 
state machine tyed into all the major 
code rutines. Becouse a state machine 
can render assocation of different 
variables bettween rutines difficalt to 
follow it is a powerfull means to set a 
cracker off track. 

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Hi Guys,
I'm getting different results 
for CRC32 on calculating in Java 

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason:
 

Sorry guys for re-posting,
using 
this link to calculate CRC32 for string 
"A" , result = 
-740712820
http://www.Planet-Source-Cod
e.com/xq/ASP/txtCodeId.4822/lngWId.1/qx/
vb/scripts/ShowCode.htm
While using 
CRC32 class in Java as:
import 
java.util.zip.*;
public class CRCTest 
{
	public static void main(String 
args[]) {
		CRC32 crc = new 
CRC32();
		String input;
		input = 
"A";
		crc.update(input.getBytes());
	System.out.println("CRC :" + 
crc.getValue());
	}
}
gives result 
as :3554254475
Can somebody explain, 
why?

Keep the Planet clean! If this comment was disrespectful, please report it:
Reason: