RSA Software protection

[boyindie86]

I am trying to write a protection procedure, which will allow me to create a licence key for our users. This licence key will ensure that the software can only run on the registered system, and will allow the user to access only specific areas of my program which is relevant to them.

I am thinking of using an RSA style approach to this where I want to be the only person who can create the registration keys. But I want to allow the program to be be able to decrypt the key. This is to prevent the average user from being able alter the key and remove any restrictions which are being imposed on the program by the license key.

The process that this would take is to produce a host id which has went through a series of tasks to distort the actual value from the user will return this code us, and from this host id I can then work out the original value of the code. Using these public and private keys I can then encrypt license key information.

However I would like to know how I would implement the private key encryption and key generation program in .NET, so that I can get this setup working in a manner which will allow me to generate keys and allow the program to decrypt keys.

Any ideas would be greatly appreciated, I know this process isn't stone wall as it doesn't protect against reverse engineering of the program.