Anti Cracking FAQ
How to make cracking your programs a little harder

Contents

1. How to make cracking your app a little bit harder...
2. More tips you might take into consideration...
3. Advanced tips given by Assembler freaks...
4. Special on Delphi VCL cracking...
5. Some notes on registration numbers...
6. How to find cracks for your apps...
7. What to do if you found a crack for your app...
8. Facts and Myths about Software pirating...
9. Thoughts and letters from crackers
10. Links of interest...

Finding out that the program on which you worked for months or years has been cracked can really hurt and demotivate.
For me as a Shareware programmer, the reason has never been that I've lost a few cents (I don't want to do propability calculations here, it might hurt even more..), no, it was simply that I've always tried to hold my programs as cheap as possible to make them affordable for everyone, even for students or freeware programmers.

Somehow I can understand the fascination of cracking programs (if you are absolutely intolerant about software crackers and hackers, please excuse, but one of my educations is Psychotherapy, and I'm always searching for reasons...) - cracking a restricted software program must be like solving a (sometimes very tricky) riddle, and you might get addicted to the feeling of solving them (I've found that when I saw my grandmother doing crossword puzzles all over the time for some months). The problem is (but at the latest, now we come to the undoubtedly illegal part of the "game"): it doesn't really satisfy the cracker if he is the the only one who knows about his "genius"...thus, he has to spread the news. He has to publish his "crack" (just see most crack packages: in most cases they just consist of: 1. the cracking utility 2. a short description 3. a big file containing claims that the producers are nothing less than the greatest ones on Earth and that the cracked program is another one which could not stop them with "its lame protection scheme".)
But now the fun is completely over: by giving out this (let's try to be fair: "study of feasibility") to other people, by spreading it via Websites, newsgroups, mailing lists, anonymous FTP, CDROM "abonnements" and whatever, they clearly damage the business of everyone who puts time and energy in their software product. Even if we assume that typical crackers wouldn't have bought your product under normal circumstances: spreading the "crack" IS criminal and no one could claim that none of the receivers or downloaders would never have bought it. It's just like if someone hands out copies of the key to your car on the marketplace - and it doesn't really matter if he does that for money or not.

In earlier days, I have never put real energy in protecting my programs against cracking, but after finding several cracks for them around, I thought to myself: why make it too easy? As a programmer, of course I know that no - really: NO! - program can ever be crack-safe, and I know that of every interesting program sooner or later cracks (or at least pirated or illegally copied versions) will be around, but at least I could try to avoid the worst mistakes. Crackers are not super-geniuses .. they are simple programmers who have learned some techniques to counteract common protection schemes - and if you know where and how crackers are searching, you can make them lose *much* time! And that's what it is about: there is no bullet-proof way to protect your programs, but you can dance on the nerves of those people until they decide for an easier target to "get the feeling"... or even go outside to enjoy the nature instead of sitting in front of the monitor the whole day. ;-)

Most of the typical 'high language' programmers don't know Assembler anymore, so the 'protection ideas' they use are in most cases quite weak.
I don't know much about Assembler myself, so I decided to open my eyes and started to collect anti-crack protection tips wherever I found them. Also I did my best to "learn from the other side" .. many of the tips you can find here I've found by studying the typical cracking techniques, the various "cracking guides" around the web and by reading protection tips given even by professional crackers themselves (some of them generously give us tips to increase their challenge). Well, I hope I've learned my lessons well enough, but also want to share my experiences with you on this page.
Some rules given here were already stated in various essays on other sites, but are listed here for completeness. Many of these apply especially to windoze, but can be "ported" to other OS'es or anywhere else.

PLEASE:

• This FAQ is just as good as the experiences that are webbed into it. If you think that I've missed some points or useful tips a typical Delphi programmer could easily add to his/her programs to improve protection, please let me know. If you allow it, I'll add it here, otherwise I'll inform you about my experiences with it.
• Don't ask me questions - might be that I'm simply too overburden to answer.
  1) As mentioned, I don't have much knowledge of the low-level stuff.
  2) I can't send you demo sources, since I don't have anything ready for a publication. If I have something, you will read it here.
  3) Finally, I will not provide anyone with any of the URLs where I've found (or found out) some of these tips. Please understand, but this is a site dedicated to programming, but not to provide "step-in's" to available cracks or even to "Cracker hunting".

• Never use meaningful procedure names such as

      function RegistrationOK: Boolean;
  	

  How intelligent and complex your code inside this function might ever be - an experienced cracker will just take about 10-20 seconds to remove it. Believe it or not.
  Alternatively, place some required code for your program in such a function. If the cracker disables the function, your program would produce incorrect results, for example.
  
  
• Avoid nagscreens or "Gotcha!" messages - this is what crackers are searching first. They will never dig through the 300K ASM instructions of your program - instead, they are first searching the location of nagscreens or your "Your evaluation time has expired!" message and start cracking there (see below for more tips about that). In some cases, it's even enough to remove the form resource from the EXE and it will show no nagscreen anymore - without any bug showing up! If you really need such a nagscren, you should build it dynamically at runtime, and generally, the only method to show the user that he is unregistered should be in the "about" dialog (some programmers also have the philosophy that nagscreens might cause your users to hate your app which would then also be very stupid).
  
  
• Never use meaningful file names such as License.Dat. Why, you say? Please start reading here. :)
  
  
• Play with asymetric encryption. Just using unusual filenames is often not enough. Good encryption, of course, could keep the cracker busy for months (if he likes).
  
  
• Add long delays. Don't warn the user right after a violation is made. Wait later, maybe until the next day or two (crackers hate that).
  
  
• Add short delays. Pause a second or two after a password entry or to your other checking routines to make brute force cracking unfeasible. Simple to do, but rarely done.
  
  
• Use checksums in DLL's and in the EXE. Have them check each other. Far away from "safe", but it just makes it harder to crack.
  
  
• Self-heal your software. You know, things like the error correction modems and hard drives use. The technology has been around for years, and no one uses it on their software? The best thing about this is that if the cracker used a decompiler, they may be looking at a listing that is no longer valid.
  
  
• Patch your own software! Change your code to call different validation routines each time. Beat them at their own game.
  
  
• Store serial numbers in unlikely places like as a property of a database field. Often heard and read: "..give it a DLL file name and store it in the System directory." Too often heard, don't use it. ;-)
  
  
• Store serial numbers in several places.
  
  
• Don't rely on the system date. Get the date of several files, like SYSTEM.DAT, SYSTEM,DA0 and BOOTLOG.TXT and compare them to the system date. Require that the time be greater than the last run (but keep in mind that many users might do Y2K-checks these days).
  
  
• Don't use literal strings that tell the user: "Sorry, but... (whatever)." These are the first things to look for. Build strings dynamically or encrypt them.
  
  
• Flood the cracker with bogus calls and hard-coded strings. Decoys are fun.
  
  
• Have fun with Spaghetti-Code simply eats his time and nerves..
  
  
• Don't use a validation functions. Every time you validate the user, write your validation code inline with the current process. That just makes more cracking for the cracker and bewares of just NUL'ing out your routine.
  
  
• Use "reserved" names. When using hard-coded keys or passwords, make them look like program code or function calls (i.e., "73AF" or "GetWindowText"). This actually works very well and confuses some decompilers.
  
  
• No "disabled" features. If your program doesn't save data in "crapware" edition, don't include a "grayed" menu item. No saving means no saving - the code should not be included in the EXE - that's it. Most programming languages offer you a really easy way to maintain several versions of your code by simply doing the following:

  	{$IFDEF trial}
  		... no action here ...
  	{$ELSE}
  		... advanced functionality for registered user ...
  	{$ENDIF}
  	

  
  
  
• Say "Goodbye" to startup/time-limits! This belongs close to the tip above - especially, since there is simply no way to protect a time-limited demo. You won't believe it - there even exist patched versions of Windows DLL's (!) which will make your demo think it has never run before on this computer. At one point or another, you will have to save your date or program start information on the computer: in a file, in the registry, somewhere - and Windows provides GREAT ways to spy on any changes made to these devices. "This is a war that can never be won." (D.Filion)
  
  
• Update often. Frequent updates mean: frequently changing code, so the typical (simple) crack which is just patching hard-coded byte positions, will possibly already be outdated when published. Also prevent uploading them to public servers, so that you have better control about where your app sits around and people don't find older versions the cracks can still use. Yes, this doesn't prevent pirates from including the version to the crack package, but IF they do so, you can at least contribute to filling up their harddisks.
  
  
• Use strong encryption. Just XORing is not really strong - use something with an algorithm that isn't easily reverse-engineered, and don't put both encryption and decryption code in your app.
  
  
• Finally, take some time to think about protecting your software. Is it really worth the protection? Wouldn't it be better to improve your software, rather than improving protections? The problem of protecting software vanishes if no one will use your software. Don't overestimate your work's "importance to the world".
  
  

• Use a serial which is several KB long of arithmetical transforms, to drive anyone trying to crack it insane. This makes a keygenerator almost impossible - Also, brute force attacks are blocked very efficiently.
  
  
• Caution with the Runtime libary! Use it fully when writing the beta versions, in the final release rewrite some functions at least to make crackers life harder.
  
  
• Mangle data. Protection that mangles data is usually a good one.
  Example: Imagine a charting program .. e.g., just disabling printing and later on enabling it basing on some registration# is the most often committed suicide. Let your thingo print. When creating data structures for printing, mangle them in some way. Unmangle them just before printing, using reg# or something other for that purpose. Even more, make this mangling subtle. Assume that you've got a pie chart to print. Don't alter anything, but add some not too big random numbers to values of data series - this is mangling then. The chart will look "not that bad", but will be otherwise unuseable (if the changes are random and on the order of 20%, for example). Finding such protection, if its connection with reg# is not self-evident can take much time. One has to delve inside your data structures and find that dreaded mangling and unmangling code.
  
  
• Traps. A method I'm not sure about, but I have heard some apps are using it: do a CRC check on your EXE. If it is modified then don't show the typical error message, but wait a day and then notify the user using some cryptic error code. When they contact you with the error code, you know that it is due to the crack. Be aware: such traps could also be activated due to virus infection or incorrect downloads. Imagine the possible aftereffects if you are blaming your potential customer for software piracy.
• Don't rely on "EXE-packers". For almost any tool which compresses EXE files (Shrinker, WWPack32, NeoLite - to list the most popular ones) there's an uncompressor around, so compressors capable for software-protection should at least support configurable encryption. Unpackers for the above (and other) tools are not very wide-spreaded, however, don't rely on them as your program's (one and only) "protection" - organized crackers usually have their harddisks full of such "tools".
  
  
• Recompile and re-release often! Especially if you are modifying your "anti-cracking" routines often, even more advanced cracks with code-searching capabilities will be useless.
  
  
• Control your own distribution! Avoid putting your apps on compilation CDs. If a crack is developed for a version that is on 30,000 CDs, that version is likely to be pirated. [by Ch.Losinger]
  
  

• The rcr/rcl trick
  If a rcr/rcl is performed on a value, it becomes much more of a pain to crack - you can't reverse it with by negating it's effects without knowing what the value of the carry flag was before the original operation. If the carry flag is created as a result of some other pain in the neck operation, you are probably onto a winner.
• Stick conditional jumps in. Everywhere.
  Conditional jumps are not fun to reverse engineer. No loops, but jumps which conditionally bypass/include portions of your wonderful key manipulation code. There is no easy inverse operation to be performed here.
• Use portions of the code as magic number tables.
  (preferably critical sections). You have no idea how annoying this can be, if you're like most crackers and like to change things around using softice (a popular cracking tool).
• Play with the cracker's mind.
  This one is fun :-) Stick series of nops in, as though you were doing self-modifying code (oh my god! what the heck! nops? Aha! Self-modifying code! Idiot spends next three years trying to find the code that should be there.). Pepper the code with junk instructions. Cut the code up into little pieces and put them all over the executable, with (preferably conditional) jumps between them. - Anything which you would find a pain in the neck.
• Detect SoftIce. Early.
  Now crash the computer. You can crash a pentium or a pentium with MMX even without a vxd by the opcode: F0 0F C7 C8 (illegal form of cmpxchg8b instruction with lock prefix). Beyond that, we have to resort to the tried and true methods. Using a vxd, take the CPU out of protected mode. Windows doesn't like that. Wonder why? .. On the other hand,
• Don't loose too much time on writing anything that will kill disassemblers or debuggers.
  Doing it is worthless, believe me, people who made them or others will soon find the way around, so shift your interest to more important stuff. Just do things which are easily and fast to afford, like the above tip.

"Let's learn something about the innards of new Borland's programming tools. This knowledge will allow us to speed up cracking sessions, as will teach shareware programmers who use Delphi to be more careful and not to happily expose their 'secrets' to curious eyes B) [..]

VCL stands for "visual component library", a library used by recent Borland visual languages as Delphi and BC++ Builder.
These environments use a proprietary resource format, that appear as 'RCDATA' when listed by Resource Workshop. These resources contain 'forms'. In Delphi jargon, forms are the windows of the program. All the info about their design is stored there. When a typical Delphi app is starting, the initialisation code creates the forms, loading the required information from the resources. Sometimes this loading is deferred - forms that aren't used very often are created and destroyed as needed.
This system is the best and the worst of Delphi. It allows a very fast way of programming but, for full-length apps, it can slow down the loading.

The really interesting part of this information is that the address of the routines - called in response to user interactions with the elements of the form - are bound at run time by name. So knowing these names we can find the appropriate addresses!

If you have cracked any Delphi apps, you have surely experienced the long chain of calls inside the library, from the breakpoints on the API calls to the "do something" code. I hoped that these addresses could help in pinpointing the relevant code."

[..describes his installation of a quite well-known Delphi-writen application..] I cracked it completely and without problems, as you are about to see :=) After first installation the weeks passed and I hadn't had the time to work on it... when I started it, I found a nasty 'Your evaluation period has expired' message :-(

The first step is to gather the information about the target exe with a resource or form spy tool. You may be tempted to investigate TVALIDATORDLG, the form where the user name and registration key is obviously input. But all you'll find is a mere dialog. The real work is accomplished from its caller: TSPLASHFORM. This is the nag window that appears at the beginning of the program, as well as when it's shutting down and from the Help->About menu.

You can select TSplashForm and look at the text representation of it. A lot of information about the buttons and labels will appear. Let's concentrate on the following part, near the end:

  object RegButton: TButton
    Left = 200
    Top = 176
    Width = 97
    Height = 25
    Caption = 'Register'
    TabOrder = 1
    OnClick = RegButtonClick
  end

Using a hex editor, I looked for "RegButtonClick" and I found it twice. The second occurrence is the resource itself, the first is within an address table:

000A4990 ____ ____ ____ BC57 4A00 0E52 6567 4275 ______.WJ..RegBu
000A49A0 7474 6F6E 436C 6963 6B__ ____ ____ ____ ttonClick_______

Some disassemblers seem to think that file is too long and it doesn't disassemble this portion of the exe correctly - however, with a special tool we can bpx on this and... right! It stops at the point just when we push the button.

A couple of instructions forward you'll find a CALL. Tracing into it you'll find a "standard stack frame" in 44ECC8:

0044ECC8 55     push ebp
0044ECC9 8BEC   mov ebp, esp
...

[description about spying the key generator routine comes next. It's been an average routine of about 10-20 Object pascal code lines.]

How this way of cracking can be avoided?

Read my tips above. The basics are: don't use automatic methods created by double clicking on the button or the object inspector. Write your code somewhere else in your program, preferably in another module, and bind it to the button using code such as:

  RegButton.OnClick := RegButtonClick;

• balance between security, feasiblity, programmability and end-user headaches
• Too long, non-alphanumeric Reg#'s tend to be continuously entered badly. Think about requiring to enter a verification field (as commonly used with passwords) or, at least, provide a "non-persistent" Reg# entry field so that the user will rewrite the Reg# each time, possibly correctly at last. Many people will just "glance-compare" the entered Reg# and the one (possibly) emailed to them, arriving at the final thought that they did enter it correctly, whereas the font is too small or they are too tired to notice that this '1' and 'l' have been interchanged (in a reg# like 'l83jjd_0)pH1lTe' )
• Refrain from any user feedback. The Reg# entry box should accept strings of any length, without any validation. Don't give crackers the knowledge about the type of your Reg# - if you do "online-verification" which shows that it's 10 chars long or that is contains only uppercase chars helps - so don't help them!
• Calculate the number of potential users! There's nothing bad like if you have to update 9,999 users because you didn't expect that there might be 10,000 of them and have to shoot out a new version which is capable for these Reg#'s...
• If your Reg# is 10 numbers long,.. .. there are 10^10 possible Reg#'s. But since your app might find let's say only 10^4 (10'000) users, you should invent an algorithm that assigns each one of 10^4 users one of 10^10 reg#'s, and does it somewhat uniformly. This prevents people and programs (some .vxd based "macro" players, for example) to be used for brute force approach. If there are only 10^4 users and you allow 10^9 "valid" Reg#s out of 10^10, on average each 10th Reg# tried brute-force will be valid, whereas on the case of 10^4 prospective users, that many valid reg#'s and space of 10^10 Reg#s, on average only each 10^6th Reg# tried brute force will be valid. Ever calculated how much time it would take to brute-force search 10^6 numbers, even using a fast machine and extremenly fast macro player (keystroke generator simulating Reg# entry and checking for results)?
• the assignment operator that assigns User# to Reg# shouldn't be trivial, and it's implementation should be done in Assembler by someone experienced both in Maths and Assembler. Remember that Delphi still allows you to directly use ASM code in your source! Then, check your operator. create graphs of how it works. Understand your own work, especially its drawbacks and vulnerabilities
• Be inventive. Don't use anything that seems simple, quick and effective unless you've come with something like Einstein's relativity theory, your approach is yes, simple, yes, quick, but no, not effective, and yes, easy to crack. I'm sorry, but we aren't geniuses and developing a good protection scheme takes some time.
• Don't have a single registration code. Make the key depend on some user-specific info - have a way to get the user info out of the registration codes. If you find a code on the web, track down the user and harass him. Threaten to do this when you give paying users their codes. [Ch.Losinger]
• Encrypt your good code - never decrypt it. And encrypt the User-Code to test against your good code... [Ch.Losinger]

• Use the Search engines
  Using search engines is one of the best methods. Most software pirates have overboarding self-confidence and even submit their illegal pages to popular search engines on the web. If you search Altavista, Lycos or especially Meta-searchers like MetaCrawler and your software is already present for more than a few months, you'll maybe have "luck" and find some "Warez Pages" which offer cracks or Registration codes for your program.
  
  
• Search pages using Free Webspace
  Software pirates, students which think it's cool to offer "Warez" and "Crackz" and other strange kinda persons especially love the free services offered by sites like GeoCities, Xoom, Tripod and others to offer their stuff. Most of them offer at least 5 MB free webspace, which is enough to provide thousands of cracks. Beside that, those sites are busy like BIG railway stations and like there, criminals feel quite safe to go after their "hobbies" there. Good for us, almost all free webspace providers also offer search features which allow you to search just all pages of their members, which is much more accurate and easier than using the big engines of which some are not kept up-to-date very good. Just connect to their main portal and start your search. If cracks exist for your program, you have very good chances to find them on some of these member pages.
  In such a case, you should contact the maintainers of the service (almost all even provide special email addresses for piracy reports (such as abuse@geocities.com).
  
  
• Search newsgroups
  Unlike what polititians are trying to suggest to the public, it's in most cases quite easy to track down who is posting cracks, serial numbers or even full licensed copies of your software in newsgroups like alt.cracks.* and others. Just let your newsreader display all header fields and check carefully where those people are writing from. Since almost any news server requires complete authentication before posting, you have good chances to find out who "hides" hinter strange names like "Hackman" or "Piratez2000". If you have no success, simply contact the webmaster of the server where the message comes from or forward him the posting, requesting action against this person.
  
  
• Make use of "Crack Search Engines"!
  The easiness of CGI and increasing success to powerful webservers leaded to some quite powerful Crack Search Engines during the recent years. They can be of enourmous help for finding cracks for your software and then starting action against the responsible persons providing these pages and cracks. Sorry, I won't provide links for those sites here, but you can't miss them during your "investigations" in those slippy parts of the web.
  Here is a link to a crack search engine - try it! Since it is not providing or linking to any cracks by itself, I decided to list it here just to show you how many cracks actually exist. If you can't find your app, don't be too happy: it's just one of a number of existing search engines.
  
  
• Use Web-Robots
  Sites like http://www.netmind.com offer robots that notify you by email when a page changes. Since you can also define result pages of, for example, AltaVista searches for a crack or key to your program, this is a cool way to get "paged" as soon as some spider hits a website of a child which "-cool, man!-" offers a crack page. You can even do that for newsgroup searches!
  
  
• Subscribe to mailing lists
  If you don't know how to go on, ask in the Anti-Warez Mailing-list or other, Shareware-related mailing lists (see my "Delphi Tips" pages for more links).
  Their members watch the activities of most popular cracking groups and have been quite active closing many of them down during the times. They will surely help you if you yourself don't have success. Shareware developers should join forces - it pays!

• Forget about the BSA (http://www.nopiracy.com, http://www.bsa.org) - these are just commercial organizations which just take "orders" for their paying clients. No, they don't work for everybody - usually they only come in to action when the target is a large firm, using software from one of their biggest clients (no prizes for guessing which one). Can you say "M$ Militia" ?
• Do internic queries on the crackers site (www.checkdomain.com), contact the sysadmin, explain the situation. If the ISP is a fair and serious one, there are chances that the crackers will receive a serious warning to remove all the illegal stuff from their sites or that it will even be closed without delay.
• If this doesn't help (seldom seen, but possible), contact the local authorities of the state where the ISP is located. Most countries even provide email addresses for reporting crime activities (like childporn, but they are also open for pirated software), or at least their police administration can be reached by email. There are good chances that the ISP will be threatened to lose his licence.
• Finally: get yourself a good glass of wine and enjoy it. You have written a good program! (otherwise no one would lose time trying to crack it)

Myth: "None of the software offered was stored on my site - I only had links to the files."
Fact: You could be liable for anything that you do that contributes to the infringement of copyrighted works. This includes facilitating a download by linking to remote files.

Myth: "I have a disclaimer on my site that protects me."
Fact: A disclaimer cannot shift your liability to someone else. You are still contributing to copyright infringement.

Myth: "I thought it was okay to download programs to try them out if I delete them within 24 hours."
Fact: This is a common Net Myth. You may only use the software as described in the end-user license provided by the software publisher.

Myth: "..there is something called 'freedom of speech' in this country..?"
Fact: Free speech refers to your right to provide opinions and original content without censure. Even so, free speech has limits. You cannot use this right to break the law. Internet sites that provide access to others' copyrighted materials - whether it's on the same site or a remote site - violate the author's right to control distribution of their works, which is against the law.

Myth: "What about "fair use"? I am only providing a service for "educational purposes."
Fact: Fair use is widely accepted to mean the reproduction of a part of a copyrighted work, not the wholesale copying of an entire program or contributing to software piracy.