The latest dll prevents decompilation, the most effective and low-cost method

At present, I want to encrypt some important dlls of the host computer software to prevent them from being decompiled by competitors. It mainly involves integrated circuits, and it is inconvenient to inform me of more information.

I need some advice to accomplish this encryption

As John Wu said, encrypted dlls need to go through some special channels when they are referenced.

You can obfuscate the dll by encryption and call it through reflection. Here is an example:

Suppose we have a project whose output type is class library, and the namespace of the project is TestDll, and there is the following class under this namespace

namespace TestDll
{
     public static class ImportantClass
     {
         private static string password = "123456";

         public static string DoSomething()
         {
             return password + "zzz";
         }

     }
}

If we don’t use encryption obfuscation method, we click Generate, then the file TestDll.dll will be generated, we create a new console application, the namespace is Test_Demo, add the dll reference, and then use the following method to call

namespace Test_Demo
{
     internal class Program
     {
         static void Main(string[] args)
         {
             string str = ImportantClass. DoSomething();
             Console.WriteLine(str);//123456zzz
             Console. ReadKey();
         }
     }
}

But we will find that both password and DoSomething in ImportantClass are visible in plain text, which is obviously not acceptable

In order to avoid the exposure of our dll implementation details, we can use ConfuserEx for obfuscation and encryption

At this time, the methods and details of the dll are all hidden. Through this method of obfuscation and encryption, the visual studio project cannot add references, so it is necessary to use Assembly to do reflection calls, and copy the encrypted dll to the application of Confuser_Demo path, and then modify the main method

     static void Main(string[] args)
     {
         string dllPath = @"C:\Users\Administrator\source\repos\TestDll\TestDll\bin\Debug\TestDll.dll";
         Assembly dll = Assembly. LoadFrom(dllPath);
         Type[] types = dll. GetTypes();
         Type type = types.Where(arg => arg.Name.Equals("ImportantClass")).FirstOrDefault();//class name
         MethodInfo methodInfo = type.GetMethod("DoSomething");//Method name
         object value = methodInfo.Invoke(null, null);// If the method has no parameters
                                                      // if the method has parameters
                                                      //object value = methodInfo.Invoke(null, new object[]{param1,param2});
         Console. WriteLine(value);
         Console. ReadKey();
     }

But as PMF said, in the final analysis, various encryption methods will only increase the difficulty of decryption for hackers, and there is always a way to crack

If you suspect that the competitor (from a remote country) hires hackers to disassemble your code, you have lost anyway. There's nothing you can do about it, except making it as hard as possible for them.

If the competitor however is a trustworthy company, they will not do that, as they have a reputation to loose and also a lot of cash in case of a lawsuit. Tech companies in western countries are very eager to make sure they follow license contracts to the letter, as they also expect that their customers do the same (and pay for their services and licenses).