Although .NET DLL files are compiled which prevents users from being able to see your proprietary source code, they are still subject to decompilation and reverse engineering attempts. If you want a higher level of security, we suggest adding an additional layer of protection for your intellectual property through the use of the following 3rd party tool below.
NinjaTrader uses and recommends their Salamander .NET Protector. This product claims to completely stop MSIL disassembly and decompilation. We use it and are extremely happy with it. We have worked out discount policy for NinjaTrader customers. Their product sells for $1,800 USD but they will license their Protector version for only $299 USD to NinjaTrader customers and partners. To take advantage of this offer please send an email to email@example.com and in the subject include "Special pricing for NinjaTrader customers".
NOTE: We have tested multiple 3rd party obfuscation and protecion tools. The product listed above is the only one that we did not run into issues with and thus we ONLY recommend and highly suggest you use this one.