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Closed 11 years ago.
I have intellectual-property coded into .net 2.0 fully-trusted assemblies (.exe + DLLs) on an end-user machine, which I would like to protect from being hacked / reverse-engineered (WebService / Cloud-Computing solutions are not an option). Below is a list of techniques I gathered in order to reach this goal.
My questions are:
Are my assumptions correct, or am I doing something wrong in one or more of the techniques?
Will this list be sufficient in order to prevent a malicious attack, or are there other protections I should add?
Thanks in advance.
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Suggested Techniques
Sign all assemblies with the same strong-name key.This has two benefits:
A. Make sure any modification to an assembly will render it useless,
B. All assemblies will have the same public key, by which they can identify each other.
Digitally sign the assemblies: Both let the users know that the executed code came from the correct source, and – add another identification component by which assemblies could identify each other.
Enforce the above by crawling up the call-stack and verifying that all callers are inside the “community”.Possible leads:
Hallgrim’s idea in this S.O. thread.
Daniel Brückner‘s addition in this S.O. thread.
This .Net Security Blog Post, which combines both solutions.
Use AOP (e.g. Spring.NET) to inject the call-stack crawling code into some/all methods.
This is mainly done because there’s no single entry point (like DllMain() for Win32 DLLs) in a .net assembly.
Obfuscate all assemblies in order to hamper reverse-engineering and reflection-execution attempts (strong name signing will be performed after obfuscation, of course).
Integrate a System.ComponentModel.LicenseProvider mechanism.
Make use of the “InternalsVisibleTo” assembly-level attribute in order to expose internals among a pre-defined set of assemblies.
Possibly use NGEN in order to convert the solution to native code.
Points to Consider
Implementing part or all of the above will most-likely introduce a performance penalty, so time-critical processing, for example, should be handled with care.
CAS seems to be irrelevant for this type of fully-trusted assemblies.
I'm afraid you won't get all the security you want. You see, this is a problem with these languages/platforms that use an itermediate language. It must be in a format that all of the runtimes implementations can consume and then produce the native code.
I've seen some blog posts about tampering signed assemblies. I haven't tried yet, but I think it works. Besides that, the obfuscation tools will just make it harder, but not impossible to extract code (altough there are some pretty good tools that make it very hard). And NGEN is not for that. You still have do distribute the original assemblies.
I think that the most efective and secure way of protect your code, is to move it to a technology that you can't decompile, for example, move your sensitive code to unmanaged C++ and use DLLImport on your C# code.
It doesn't mean that you shouldn't try to protect your code, but you should have in mind that you won't be 100% protected. If you can't afford to rewrite your sensitive code in another language, go with obfuscation and signing. You can't get much more secure than that.
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Overview
Over the last 3 years we've built a full-featured software package in C#
Our software was architected in such a way that it handles a lot of the low-level plumbing required for the application so that our developers can focus on the specific problem they are trying to solve rather than all the minutiae. This has improved development and release times significantly
As such, the code is broken out into various projects to give us logical separation (e.g. a front-end MVC app, a services layer, a core framework layer, etc)
Our core framework project has a lot of functionality built into it (the main 'guts' of the application) and it has been carefully organized into various namespaces that would be familiar to all (e.g. Data Access, IO, Logging, Mail, etc)
As we initially built this, the intent was always for our team to be the target audience, our developers coding the various new pieces of functionality and adding to the framework as needed.
The Challenge
Now the boss wants to be able to open our codebase up to 3rd party developers and teams outside of our own company. These 3rd party folks need to be able to tap directly into our core libraries and build their own modules that will be deployed along with ours on our servers. Just due to the nature of the application it is not something we could solve by exposing functionality to them via REST or SOAP or anything like that, they need to work in an environment much like our own where they can develop against our core library and compile their own DLLs for releases
This raises many concerns and challenges with regard to intellectual property (we have to be able to protect the inner workings of our code), distribution, deployment, versioning and testing and releases and perhaps most important how we will shape the framework to best meet these needs.
What advice would you offer? How would you approach this? What kind of things would you look to change or what kind of design approach would you look to move towards? I realize these questions are very open-ended and perhaps even vague but I'm mainly looking for any advice, resources/tutorials or stories from your own background from folks who may have faced a similar challenge. Thanks!
I'm not sure the MEF answer really solves your problem. Even using Interfaces and MEF to separate the implementation from the contracts, you'll still need to deliver the implementation (as I understand your question), and therefore, MEF won't keep you from having to deliver the assemblies with the IP.
The bottom line is that if you need to distribute your implementation assemblies, these 3rd parties will have your IP, and have the ability to decompile them. There's no way around that problem with .NET, last I checked. You can use obfuscation to make it more difficult, but this won't stop someone from decompiling your implementation, just make it harder to read and understand.
As you've indicated, the best approach would be to put the implementation behind a SaaS-type boundary, but it sounds like that's out of the question.
What I will add is that I highly recommend developing a robust versioning model. This will impact how you define your interfaces/APIs, how you change them over time, and how you version your assemblies. If you are not careful, and you don't use a combination of both AssemblyVersion and AssemblyFileVersion for your assemblies, you'll force unnecessary recompiles from your API clients, and this can be a massive headache (even some of the big control vendors don't handle this right, sadly). Read up on these, as they are very important for API/Component vendors in my opinion.
NDAs and/or License Agreements are another way, as #trailmax indicates, if you feel your users will respect such agreements (individuals vs. companies may view these type of agreements differently).
Oh, also make sure that you Sign your Assemblies with a Strong Name. And to do this, you'll probably need to establish a strategy to protect your Signing Keys. This seems simple at first, but securing your signing keys adequately is not as easy as it appears at first blush. You often have to have multiple sets of keys for different environments, need to incorporate the keys into CI/CD systems, and need to insure access to the release keys is tightly held.
As #HighCore already said, implement interfaces for all the stuff you want to expose. Put them into a separate project/repository and give read-only access to the project/repository. But your interfaces must be properly documented, otherwise it might be painful for other guys.
This way your code is not really visible to them, and they can still work on it.
If that does not work-out, and you are forced to show them your code, get them to sign NDA. NDA should state that your code is yours and they can't redistribute it in any way.
I guess my answer is as vague as the question, but gives you some ideas.
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Closed 10 years ago.
If so, how can i protect my code from being decompiled?
Or from being reflected? If actually the two are very different from each other.
Tools like Dotfuscator for the .Net framework, do they help your code from being decompiled? Does that mean that i can still reflect on it and see it's contents??
You can't ever stop either. You can make it so that decompiling the program returns incomprehensible and confusing code, but it still will be valid code that results in a program that functions identically to yours. Making subtle changes will be harder, but not impossible. Doing that is called obfuscation, which is what those tools are.
Obfuscators go around doing things like changing all variable names to meaningless alphanumeric values, performing all sorts of code refactors that don't change how the code works, but just are things that do the same thing in a different way (and is somehow harder for humans to understand, but not computers). They can also add in code that doesn't do anything, just to confuse people, etc. Different obfuscators will do all sorts of different things, and they can have some differences such as, whether or not they accidentally introduce bugs, what their effect is on the size of the compiled program, and how close the compiled program is from the original source (which, granted, is somewhat subjective).
It has the same effect on reflection, although reflecting and decompiling are completely different.
First, let's go over the difference between the two terms.
Reflection provides the ability to discover type information within an assembly at runtime. This is part of the framework, and makes possible features such as code completion in the IDE, references between assemblies, etc. It's also used in frameworks, such as ASP.NET (you can basically refer to classes, or web controls, in markup and instances will be dynamically created at runtime using reflection). This is also used in serialization, which is the core of web services, WCF, the web part framework, session state, AJAX, and more.
Decompiling is a term for converting machine code to a higher-level, human readable code. The .NET framework uses an intermediary language (IL) which is a machine-agnostic low level language somewhat similar to assembly, minus CPU specific things like registers. The runtime itself is what actually takes this IL and compiles it to the code that's actually specific to the local machine through a process called JIT'ing. Obviously, your code has to be in IL for the runtime to understand it (though there are processes to pre-compile or pre-JIT IL code).
There is no overlap between the two. Reflection only uses the metadata stored in the assembly's manifest, it does not look at the actual IL code the compiler generated. You'd never be able to use reflection to infer how a method was actually implemented
With that said, there are various tools to obfuscate IL code, making it harder to understand. One popular one tool Dotfuscator.
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Closed 11 years ago.
I know this project.The question is that "Can we create a real OS with Managed Code or the os that will create with this project is a hello world os?"
Operating Systems need to have full control on hardware.Can we do it with this one?
If there are any another project please tell me
Cosmos Project
Yes it can be done - see Singularity which is (was) a Microsoft research project to create an entirely managed operating system in "Sing#" (an extended version of "Spec#" which is itself an extension of C#). Its worth stressing that this was just a research project into the concept, and was never intended as a "full" operating system of the likes of Windows or Max OSX.
The source code is available on CodePlex - you can download the code, build it and run it yourself in an emulator (I've done it myself, its well documented and relativley easy although I can't remember the exact steps myself).
Parts of the system were written in assembly / C, specifically the bootloader and the lowest level x86 interupt dispatch code however this is essentially all but unavoidable (it is by its very nature very platform dependant - something needs to write the x86 instructions to control and respond to basic hardware). The low level interrupts are also not particularly interesting in terms of how the operating system actually functions, so I personally don't consider this as cheating the "entirely managed" definition.
Looking on the Wikipedia page for Singularity there are also 5-6 similar projects, including Cosmos and a couple of similar attempts that use Java instead of C#.
The focus of Singularity OS was on security and dependency, however whats also impressive is that according to some basic benchmarks in An Overview of the Singularity Project1 (PDF) the performance of their archetecture was actually comparable to that of other "more conventional" operating systems:
... these numbers demonstrate that architecture that we
proposed not only does not incur a performance penalty, but is often as fast as or faster than more
conventional architecture. In other words, it is a practical basis on which to build a system.
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Closed 11 years ago.
I want to implement another debugger (language) for .NET (it's just for academic reason, so that it can implement just a part of a language). I myself like to implement NS2 (network Simlator 2) script for .NET in which anybody can write ns2 script and debug it with .NET
I read this article in stackoverflow and it is far from what I'm looking for.
Here is the requirement
have some predefined keywords (e.g: for, while, if ...)
check the correct form of the statements (e.g: for(start;end;counter){commands} ...)
diffferent colour for different types of statements
ability to add to any IDE (e.g: implementatin like add-in or as a dll or ...(I have no idea))
many other thing that is not necessary for now
How can I do this?
Update : I'm not sure that you got my point, take a look at this, it is very close to what I am looking for.
It will not be an easy task. However: The Dragon Book is probably a good place to start (assuming you've got sufficient computer science background for a compiler theory book to make much sense to you). Compiler Construction: Principles and Practice is also a good text.
You'll want to compile to CIL (common intermediary language). This handy wiki article outlines the CIL instruction set. Debugging your intermediate code against the CLR... well, that's where the StackOverflow article you've linked will come in handy =)
That'll cover your first two bullets (and consume a big chunk of your life).
The next two are different issues, but the easiest way to 'make it go' would probably be to define a syntax for an existing text editor, and set up a macro in the program to call your compiler. I'd recommend TextPad, though I'm sure opinions on a configurable general-purpose text editor will vary among the community ;)
Designing a full IDE with all of the features you've come to know and love in your environment could be quite a task ... or you could try to build an eclipse plugin. Personally (assuming you can design your language and learn something from it), I'd just stick with syntax highlighting in TextPad.
There is more and more interest in this area and in fact there is an active project by Microsoft Research that is looking at this on building a common infrastructure to build compiler (and debugger) for custom languages targetting .NET
http://cciast.codeplex.com/
I have used the infrastructure myself but not an expert in compiler technology. Hope this gives you a good starting point and you may find the discussion forum useful to share idea with like minded people.
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Closed 12 years ago.
I want to create an encryption software , I want to know can hacker find a password for a encrypted file ?
The short answer is : If there's a reward that's worth it then someone with enough resources can crack it.
Do not create your own algorithm. I repeat do not create your own.
Use an existing library. Many many millions have gone into getting this has difficult to break as possible and unless you have a educational interest in learning how to create them I would strongly urge you to reconsider and use an off the shelf package.
Chances are any algo you come up will be easily broken as crackers have many advanced tools to hand.
I repeat do not create your own.
Please see this question for more info. What techniques do you use when writing your own cryptography methods?
Since you are using C#, probably yes. Anybody can look at a .NET app's source code through Reflector. Using that, one can reverse engineer your encryption algorithm.
If ever you are going to use other languages, lets say some which are not easy to decompile. Decent crackers can debug your program and look into how the encryption is done, through debugging. So, the answer is still Yes.
If you're gonna use C#, or any .NET language, obfuscate your code using an obfuscator.
Yes. He can:
guess it
see it written down somewhere
ask the user for it
discover it by analysing the behaviour of the algorithm
convince the user to change the password to one he knows
You need to design your software and the way it's used to make these as hard as possible. Not all of the above can be solved in software.
Erm... Well... What do you want to know? HOW a hacker can find a password or IF a hacker can find a password. Considering this, make yourself clear and rephrase your question.
First, check out what encryption actually means. There are a lot of possibilities to encrpyt a {file, string, data, whatever}. An important question is: when does your data become invalid? If it is of no use anymore after one week then you do not need a strong encryption, maybe you can write something from scratch. If it still must be encrypted (undecrypted, unhacked) after like two years, you should use an encryption technique like RSA which has its foundation in mathematics and thus has been proven to be unhackable in a time that could give a hacker an advantage by having access to your data.
My answer is based on these two facts: unless the cracker has access to a network of thousands of hosts or a quantum computer, RSA should do the trick.
Peace