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I know this question is asked many times, I read every question but didn't find solution for my case.
Our team made an application in .Net 4.7.2 and in few days we have to deploy it. We are using web services, so even if user cracks license system, they won't be able to access services. Our only concern is to prevent its duplication (someone can resell under his brand and this happened to our previous versions) as these web services(simple CRUD operations) are very easy to implement, so someone can change URL to there servers and duplicate these services. For protection against this, we are using encrypted calls to server. Problem we are facing now is to protect this encryption algorithm and obfuscation is not enough for this.
Again our only concern is to protect code. Sorry for bad English.
I know about .Net Reactor but there are many unpacker that can unpack .Net reactor protected application. I don't know if these unpacker work on current version.
Should I use .Net Reactor?
Is there any solution out there to convert .Net 4.7 code to native code or any other way to prevent this(except for obfuscation or Ahead Of Time Compilation)?
Code you distribute can/will be analized (even copied/cloned) by all sorts of people, no way around that. Even only distributing compiled binaries is not a real hurdle for a determined adversary. Semi-compiled languages like Java's JVM or .NET often keep a lot of source information in the binary, to the point that sometimes decompiling to understandable source is more or less automatic. Source obfuscation can help a bit here, but that introduces another step (and possibly introduce bugs!), but an attacker will probably only be interested in localized swaths of code anyway.
If the services are "easy to duplicate", as you state, I wonder if they are really that valuable. Most extremely valuable 'net services use simple, even well known and publicly available protocols (as in "download a library to use our services here") to access them, but if I'd create my own clone of e.g. YouTube I'll get nowhere, the value is not in the interface but in the service offered.
Re keep encryption secret: Never forget Kerckhoffs' rules. In particular, homebrew encryption is usually ridiculously easy to break, getting at the exact algorithm is possible with some ingenuity even if it is only in hardware (like the MiFare card hack), and unless it has been carefully designed, it will be broken in short order. Do use the accepted cryptographic tools, like AES, Diffie-Hellman, RSA. Yes, it might be incur in some extra costs (in any case there are free/open source alternatives available for everything of interest), but it is much, much more secure than anything you could come up with.
I built a simple demo application in C# using a modular approach so it consists of one executable and a couple of DLLs. Suppose I put it in a zip file and hand it over to somebody, with the sole purpose they can try out the demo application simply by extracting the file and doubleclicking the exe.
Now, to my understanding everybody that gets the application and the DLLs, can just add a reference to the DLLs in a Visual Studio project, and then start using whatever functions/classes they have as long as they are declared public. And hence, they can get access to a lot more than what I want them to access.
Is there a way to disable this, and get a system that is somehwat like with C++ DLLs (e.g. I can give anyone a lot of C++ DLLs and they'll have a rather hard time using the functions/classes in it if they do not have the header files)? Can I somehow strip the DLLs so that they are still usable by the exe, but do not expose references? Or are there attributes or so that I can use in the code that say "this class is usable only be DLLs/exes built by me"?
You could use the InternalsVisibleToAttribute and not make anything public, but...
You're mistaken if you think that anything stops someone from using non-public classes from your DLL. An application with full-trust can access private and internal content no problem, or they can decompile and rebuild the DLL with everything public.
People will suggest obfuscation, but that doesn't do much more.
You should read this answer (and question, but mostly answer): C#: How to Make it Harder for Hacker/Cracker to Get Around or Bypass the Licensing Check?
One possible solution is to leave public only the method that is supposed to be called from the executable. Everything else could be private or internal. You could also obfuscate the assembly. But remember that no matter what you do, there is always the possibility of using Reflection to invoke any method inside the assembly. Of course if it is obfuscated it will be a little harder but not impossible.
I think you can use Friend assemblies for that.
You may also obfuscate internals of your dlls so it become really hard to do reverse engineering and decompile your assemblies. Tools like Dotfuscator will rename all function/variable names inside your compiled dll to something like a0002345 so reading it will be really exhaustive.
Please notice that none of methods gives you 100% protection as still it is possible to use .NET reflection routines to access and use your private and internal classes. However making stuff internal or private will stop majority developers using those classes. Use obfuscation to stop advanced engineers who tries to dig into your compiled sources. In theory protection is considered safe enough if decompiling effort is greater than effort for writing similar tool from scratch. If somebody can't read your dlls the one won't be able to know how to use it.
No, sorry, not.
You could do ilmerge followed by obfuscation (I'm not sure what tool) for something similar.
One if the first things I learned when I started with C# was the most important one. You can decompile any .NET assembly with Reflector or other tools. Many developers are not aware of this fact and most of them are shocked when I show them their source code.
Protection against decompilation is still a difficult task. I am still looking for a fast, easy and secure way to do it. I don't want to obfuscate my code so my method names will be a,b,c or so. Reflector or other tools should be unable to recognize my application as .NET assembly at all. I know about some tools already but they are very expensive. Is there any other way to protect my applications?
EDIT:
The reason for my question is not to prevent piracy. I only want to stop competitors from reading my code. I know they will and they already did. They even told me so.
Maybe I am a bit paranoid but business rivals reading my code doesn't make me feel good.
One thing to keep in mind is that you want to do this in a way that makes business sense. To do that, you need to define your goals. So, exactly what are your goals?
Preventing piracy? That goal is not achievable. Even native code can be decompiled or cracked; the multitude of warez available online (even for products like Windows and Photoshop) is proof a determined hacker can always gain access.
If you can't prevent piracy, then how about merely reducing it? This, too, is misguided. It only takes one person cracking your code for it to be available to everyone. You have to be lucky every time. The pirates only have to be lucky once.
I put it to you the goal should be to maximize profits. You appear to believe that stopping piracy is necessary to this endeavor. It is not. Profit is simply revenue minus costs. Stopping piracy increases costs. It takes effort, which means adding cost somewhere in the process, and so reduces that side of the equation. Protecting your product also fails to increase your revenue. I know you look at all those pirates and see all the money you could make if only they would pay your license fees instead, but the reality is this will never happen. There is some hyperbole here, but it generally holds that pirates who are unable to crack your security will either find a similar product they can crack or do without. They will never buy it instead, and therefore they do not represent lost sales.
Additionally, securing your product actually reduces revenue. There are two reasons for this. One is the small percentage of customers who have trouble with your activation or security, and therefore decide not to buy again or ask for their money back. The other is the small percentage of people who actually try a pirated version of software to make sure it works before buying. Limiting the pirated distribution of your product (if you are somehow able to succeed at this) prevents these people from ever trying your product, and so they will never buy it. Moreover, piracy can also help your product spread to a wider audience, thus reaching more people who will be willing to pay for it.
A better strategy is to assume that your product will be pirated, and think about ways to take advantage of the situation. A couple more links on the topic:
How do i prevent my code from being stolen?
Securing a .NET Application
At work here we use Dotfuscator from PreEmptive Solutions.
Although it's impossible to protect .NET assemblies 100% Dotfuscator makes it hard enough I think.
I comes with a lot of obfuscation techniques;
Cross Assembly Renaming
Renaming Schemes
Renaming Prefix
Enhanced Overload Induction
Incremental Obfuscation
HTML Renaming Report
Control Flow
String Encryption
And it turned out that they're not very expensive for small companies. They have a special pricing for small companies.
(No I'm not working for PreEmptive ;-))
There are freeware alternatives of course;
Host your service in any cloud service provider.
How to preventing decompilation of any C# application
Pretty much describes the entire situation.
At some point the code will have to be translated to VM bytecode, and the user can get at it then.
Machine code isn't that much different either. A good interactive disassembler/debugger like IDA Pro makes just about any native application transparent. The debugger is smart enough to use AI to identify common APIs, compiler optimizations, etc. it allows the user to meticuloulsy rebuild higher level constructs from the assembly generated from machine code.
And IDA Pro supports .Net to some extent too.
Honestly, after working on an reverse engineering ( for compatibility ) project for a few years, the main thing I got out of my experience is that I probably shouldn't worry too much about people stealing my code. If anyone wants it, it will never be very hard to get it no matter what scheme I implement.
No obsfuscator can protect your application, not even any one described here. See this link, it's an deobsfuscator which can deobsfuscate almost every obsfuscator out there.
https://github.com/0xd4d/de4dot
The best way which can help you (but remember that they are also not full prof) is to use mixed codes, code your important codes in unmanaged language and make a DLL like in C or C++ and then protect them either with Armageddon or Themida.
Themida is not for every cracker, it's one of the best protector in the market, it can also protect your .NET software.
I know you don't want to obfuscate, but maybe you should check out dotfuscator, it will take your compiled assemblies and obfuscate them for you. I think it can even encrypt them.
I've heard about some projects that directly compile IL into native code.
You can get some additional info from this post:
Is it possible to compile .NET IL code to machine code?
We use SmartAssembly for .NET protection of an enterprise level distributed application, and it has worked great for us.
If you want to fully protect your app from decompilation, look at Aladdin's Hasp. You can wrap your assemblies in an encrypted shell that can only be accessed by your application. Of course one wonders how they're able to do this but it works. I don't know however if they protect your app from runtime attachment/reflection which is what Crack.NET is able to do.
-- Edit
Also be careful of compiling to native code as a solution...there are decompilers for native code as well.
Do you API?
Instead of trying to protect your one ddl file in one of your products on all of your customers devices, why not create an API service for your precious product features? Let the actual product that is saved on a device consume that API to deliver the product as you want it.
I Think this way you are 100% sure that your code is not decompiled and you set your own limits in your API so that developers / hackers don't consume your API in a way you don't want it.
Sure is some more work, but in the end, you are in control.
If someone has to steal your code, it likely means your business model is not working. What do I mean by that? For example, I buy your product and then I ask for support. You're too busy or believe my request is not valid and a waste of your time. I decode your product in order to support my relative business. Your product becomes more valuable to me and I prioritize my time in a way to resolve the business model for leveraging your product. I recode and re-brand your product and then go out and make the money that you decided to leave on the table. There are reasons for protecting code, but most likely you are looking at the problem from the wrong perspective. Of course you are. You're the "coder", and I'm the business man. ;-) Cheers!
ps. I'm also a developer. i.e. "coder"
I know this is old but, Themida is the most advanced anti-cracking software I've ever used.
It's not free, though.
Besides the third party products listed here, there is another one: NetLib Encryptionizer. However it works in a different way than the obfuscators. Obfuscators modify the assembly itself with a deobfuscation "engine" built into it. Encryptionizer encrypts the DLLs (Managed or Unmanaged) at the file level. So it does not modify the DLL except to encrypt it. The "engine" in this case is a kernel mode driver that sits between your application and the operating system. (Disclaimer: I am from NetLib Security)
It's a standard practice to decompile and reverse engineer .net assemblies.
I'd like to release some plugin assemblies that will add to existing applications, but I don't want them to be utilized by others.
What are some ways I can hide the source of these assemblies?
It's theoretically impossible to achieve 100% protection unless you control the target hardware. If the CPU is able to execute it, given enough time and knowledge, a human being can read it too. This is not even limited to C# (although it's usually easier to do in managed languages). You can use an obfuscator like Dotfuscator or XenoCode to make it harder to understand the decompiled code. If you're really concerned, you should move to a server-based application.
You can use an obfuscator tool, it will help but reverse engineering will still be very possible.
Your users' computer needs to know what it needs to do, so you have to tell it. The owner of the computer has total control over it, and can therefore know himself what you told the computer to do, and he can tell it to do something else.
There is a way to hide the data, its called steganography. There's an author of a number of articles covered on CodeProject, who wrote a framework for doing exactly this. The title of the articles were 'Steganography ' in a series from 1 up to 12 I think. This is the website that is affiliated with the author.
There is a also a obfuscator called 'Phoenix Protector', found here, which can obfuscate the .NET code, personally, I have not tried it but it sounds good.
Hope this helps,
Best regards,
Tom.
It's software; anything is possible. You can encrypt your binaries, and then decrypt all or part of them into your application at runtime. It's not foolproof, but it's up to you to decide how draconian you want to be.
You can write an app that will host CLR using the CLR COM api, that way you can first load and decode the assembly at the native code level. If you reinforce the native loader using several anti-reverse engeneering techniques, you can achieve good enough security.
At the very least, you should obfuscate your dlls to prevent hackers & competitors from viewing and making sense of your code. Obfuscation is not 100% foolproof, but it presents a big enough obstacle in their path.
Some obfuscators such as Crypto Obfuscator have a feature of embedding all dlls in the main exe so your dlls are not explicitly visible and available on disk to open in reverse-engineering tools such as Reflector.
I was thinking about obfuscating a commercial .Net application. But is it really worth the effort to select, buy and use such a tool? Are the obfuscated binaries really safe from reverse engineering?
You may not have to buy a tool - Visual Studio.NET comes with a community version of Dotfuscator. Other free obfuscation tools are listed here, and they may meet your needs.
It's possible that the obfuscated binaries aren't safe from reverse engineering, just like it's possible that your bike lock might be breakable/pickable. However, it's often the case that a small inconvenience is enough to deter would be code/bicycle thieves.
Also, if ever it comes time to assert your rights to a piece of code in court, having been seen to make an effort to protect it (by obfuscating it) may give you extra points. :-)
You do have to consider the downsides, though - it can be more difficult to use reflection with obfuscated code, and if you're using something like log4net to generate parts of log lines based on the name of the class involved, these messages can become much more difficult to interpret.
Remember that obfuscation is only a barrier to the casual examiner of your code. If someone is serious about figuring out what you wrote, you will have a very hard time stopping them.
If you have secrets in your code (like passwords), you're doing it wrong.
If you worried someone might produce your own software with your ideas, you'll have more luck in the marketplace by providing new versions that your customers want, with technical support, and by being a partner to them. Good business wins.
At our company we evaluated several different obfuscation technologies, but they all had problems. The biggest problem was that we rely a lot on reflection, e.g. to dynamically create grids based upon property names.
So all of the obfuscators rename things, you can disable it of course, but then you lose a lot of the benefit of obfuscation.
Also, in our code we have a lot of NUnit tests which rely on a lot more of the methods and properties being public, this prevented some of the obfuscators from being able to obfuscate those classes.
In the end we settled on a product called .NET Reactor
It works very well, and we don't have any of the problems associated with the other products.
"In contrast to obfuscators .NET Reactor completely stops any decompiling by mixing any pure .NET assembly (written in C#, VB.NET, Delphi.NET, J#, MSIL...) with native machine code. In detail, .NET Reactor builds a native wall between potential hackers and your .NET code. The result is a standard Windows based, not MSIL compatible, file. The original .NET code remains intact, well protected by native code and invisible for prying eyes. The original .NET code is not copied on harddisk at any time. There is no tool which is able to decompile .NET Reactor protected assemblies."
The fact that you actually can reverse engineer it does not make obfuscation useless. It does raise the bar significantly.
An unobfuscated .NET assembly will show you all the source, highlighted and all just by downloading the .NET Reflector. Add obfuscation to that and you'll reduce very significatively the amount of people who'll be able to modify the code.
It depends on you are you protecting yourself from. If you'll ship it unobfuscated, you might as well open source the application and benefit from marketing. Shipping it obfuscated will only allow people to relatively easily generate modified binaries through patches instead of being able to steal your code and create a direct competitor. Getting the actual source from obfuscated code is very hard, depending on the obfuscator, of course.
I think that it depends on the type of your product. If it is directed to be used by developers - obfuscation will hurt your customers. We've been using the ArcGIS products at work, and all the DLLs are obfuscated. It's making our job a lot harder, since we can't use Reflector to decipher weird behaviors. And we're buying customers who paid thousands of dollars for the product.
So please, don't obfuscate unless you really have to.
Things you should take into account:
Obfuscation does not protect your code or logic. It just makes it harder to read and understand.
Obfuscation does no one stop from reverse engineering. It just slows the process down.
Your intellectual property is protected by law in most countries. So if an competitor uses your code or specific implementation, you can sue him.
The one and only problem obfuscation can solve is that someone creates a 1:1 (or close to 1:1) copy of your specific implementation.
Also in an ideal world reverse engineering of an obfuscated application is economical unattractive.
But back to reality:
There exists no tool on this planet that stops someone from copying user interfaces, behaviors or results any application provide or produce. Obfuscation is in this situations 100% useless
The best obfuscator on the market cannot stop one from using some kind of disassembler or hex editor and for some geeks this is pretty good to look into the heart of an application. It's just harder than on an unobfuscated code.
So the reality is that you can make it harder and more time consuming to look into your application but you won't really get any reliable protection. Regardless if you use a free or an commercial product.
Advanced technologies like control flow obfuscation or code virtualization may help to make understanding of logic sometimes really hard but they can also cause a lot of funny and hard to debug or solve problems. So they are sometimes more like an additional problem than a solution.
From my point of view obfuscation is not worth the money some companies charge for their products. If you want to nag casual developers, open source obfuscators are good enough. If you want to make it as hard as possible to look into the heart of your applications, you need to use cryptographic containers with virtual execution environments and virtual filesystems but they also provide attack vectors and may also be a source for a bag full of problems.
Your intellectual property and your products are in most countries protected by law. So if there's one competitor analyzing and copying your code, you can sue him. If a bad guy or and hacker or cracker takes your application you are pranked - but an obfuscator does not make a difference.
So you should first think about your targets, your market and what you want to achieve with an obfuscator. As you can read here (and at other places) obfuscation does not really solve the problem of reverse engineering. It only makes it harder and more time consuming. But if this is what you want, you may have a look to open source obfuscators like e.g. sharpObfuscator or obfuscar which may be good enough to nag casual coders (a List can be found here: List of .NET Obfuscators on Wikipedia).
If it is possible in your scenario you might also be interested in SaaS-Concepts. This means that you provide access to your software but not the software itself. So the customer normally has no access to your assemblies. But depending on service level, security and user base it can be expensive, complex and difficult to realize a reliable, confident and performant SaaS-Service.
No, obfuscation has been proven that it does not prevent someone from being able to decipher the compiled code. It makes it more difficult to do so but not impossible.
I am very confortable reading x86 assembly code, what about people that is working with assembly for more than 20 years ?
You will always find someone that only need a minute to see what your c# or c code is doing...
Just a note to anyone else reading this years later - I just skimmed through the Dotfuscator Community Edition (that comes with VS2008) license a few hours ago, and I believe that you cannot use this version to distribute a commercial product, or to obfuscate code from a project that involves any developers other than yourself. So for commercial app developers, it's really just a trial version.
...snip...
these messages can become much more
difficult to interpret
Yes, but the free community edition that comes with Visual Studio has a map functionality.
With that you can back track the obfuscated method names to the original names.
I've had success putting the output from one free obfuscator into a different obfuscator. In Dotfuscator CE, only some of the obfuscation tricks are included, so using a second obfuscator that has different tricks makes it more obfuscated.
It's quite simple to reverse engineer a .net app using .net reflector - since the app will generate VB, VC and C# code straight from the MSIL, and it's possible to pull out all kinds of useful gems.
Code obfuscators hide code quite well from most reverse engineering hacks, and would be a good idea to use on proprietary and competitive code that adds value to your app.
There's a pretty good article on obfuscation and it's workings here
This post and the surrounding question have some discussion which might be of value. It isn't a yes-or-no issue.
Yes you definitely should. Not to protect it from a determined person, but to get some profit and have customers. By the way, if you reach a point here someone tries to crack your software, that means you sell a popular software.
The problem is what tool to choose for the job. Check out my experience with commercial obfuscators: https://stackoverflow.com/questions/337134/what-is-the-best-net-obfuscator-on-the-market/2356575#2356575
Yes, we do. We use BitHelmet obfuscator. It's new, but it works really well.
But is it really worth the effort to select, buy and use such a tool?
I found Eazfuscator cheap (free), and easy to use: took about a day.
I already had extensive automated tests (good coverage), so I reckon I could find any bugs that are/were introduced by obfuscation.