Professional Visual Studio® 2008

Chapter 29. Obfuscation

If you've peeked under the covers at the details of how .NET assemblies are executed, you will have picked up on the fact that instead of compiling to machine language (and regardless of the programming language used), all .NET source code is compiled into the Microsoft Intermediary Language (MSIL, or just IL, for short). The IL is then just-in-time — compiled when it is required for execution. This two-stage approach has a number of significant advantages, such as allowing you to dynamically query an assembly for type and method information, using reflection. However, this is a double-edged sword, because this same flexibility means that once-hidden algorithms and business logic can easily be reverse-engineered, legally or otherwise. This chapter introduces obfuscation and how it can be used to protect your application logic. Be forewarned, however. Obfuscation provides no guarantees, because the IL must still be executable and can thus be analyzed and potentially decompiled.