What's the best approach to Protect Custom .NET Components with License ?

Question

What's the best approach to Licensing Custom .NET Components or applications for selling ?

• Closed Source
• 2 licensing mode :
  • Trial limited features license (free)
  • Full featured

Answer 1

There is a lot of missing detail here.

Are you licensing from someone or trying to create a license?

Open source, closed source, selling? If selling, do you provide source?

What is the final usage of the component / application? Are you hosting it (like a multi-tenant site) or is it more COTS?

What are your competitors doing with their sales model? Does it appear to be working for them? e.g. does it sound reasonable? <- emulate that.

As you answer those questions, you'll find the license that fits your needs.

Answer 2

GPL. Or declaring it public domain. Or a 24-page EULA that restricts the ability of users to shave while using the component. Or something like that.

Why don't you tell us what you are trying to do, what the intended uses are, and what you'd like to have happen?

Answer 3

As for a "Closed Source" scenario consider using obfuscation. I've been using SmartAssembly and very satisfied with results.

As for licensing modes. You are speaking about .net components so the target audience are developers. I don't think they will deal with free limited trials. If you are going to sell something valuable to developer community get ready to see a "Full Featured" version on Rapidshare or torrents.

I would recommend concentrating on support and frequent updates/enhancements rather than protection. In most cases "business" buys support rather than binaries.

If you need some tool titles why don't you just google for that? ".net licensing" query will give you tones of links.

Hope that helps.

Answer 4

Hi David,

When you're giving out trials of your software that are upgradeable to full versions (in other words assemblies that contain all features), there's not a whole lot you can do to prevent someone from hacking it in the end. (with .net it's even easier then with native assemblies).

Signing & Obfuscation is the only way to prevent it from being reverse engineered in a very readable form but just using something like reflector will basically give you the complete.

One of the simplest ways to keep up the appearance of licensing is to:

• use public/private key encryption to save licensing information (expiration date, enabled features, etc) into a file
• include the public key in the assembly
• decode the encrypted information on the start of your application to check if someone is licensed to use your application.
• generate licenses when necessary with your private key and distribute those files (or keys if the data is small enough)

As an alternative you can include the licensing information in clear text with a hash code (this is the licensing key, algorithm should also support public/private key) in clear text with the application, and only check if the licensing information matches the hash code.