Introduction to SLP Services Internals

The above table explains the solution and benefits provided by SLP Services for an ISV (Independent Software Vendor). Let's see how SLP Services provides code protection.

On .NET platform, whatever the code is written will be converted to MSIL. CLR finally converts this MSIL code to platform-specific native code using JIT compilation. This way of compiling provides lot of advantages. At the same time, the MSIL code will also have lot of structure and information inherited from base language like C# or VB.NET. As a result, MSIL code will be decompiled easily back to high level language using reverse engineering techniques. Below figure shows the phases of running a .NET application:



So, we use to share the assemblies having IL code to the clients. By using tools like reflector, it can be decompiled to hack our code or trade secrets. SLP services addressed this problem by providing security to sections of code having sensitive data like connection strings, complex algorithms etc. Traditionally, there are few ways to secure our code without using SLP code protection services. We will have a look at each of those strengths and weaknesses:

Obfuscation: This technique alters the IL code such way that decompiled code is hard to read for most people. It will alter names of classes, methods and changes flow of code having same end result having difficulty in reading. Reverse engineering is still possible, but difficult to do it.

Encryption: This technique encrypts the contents of an assembly by using tools provided by Microsoft. But, it does require decrypting for execution by CLR. So, there is performance hit. It is also possible for a hacker to get decryption key of the assembly by using automated tools.

Code Splitting: This technique splits the code having sensitive information passed on using some special security like hardware or smartcard. It is costs high and inefficient in certain scenarios.

All above techniques are having some weaknesses. So, Microsoft provided an efficient code protection technique using SVML (Secure Virtual Machine Language). SLP Code Protector application part of SLP Services converts IL code to SVML code. This SVML code cannot be decompiled. Since MSIL specification is known to all for decompiling it.
Where as SVML code changes with each unique SVML Permutation.

Lets' see how SVML provides security to our code from decompiling:

It is suggested to use SLP Code Protector on methods having sensitive data only. Since, performance will be reduced, to decrypt and execute protected code. I am ending the things here. I hope this article will be helpful for all.