nonexportable certificate/private key

[Joe Bloggs]

I want to be able to provide a full/indefinite use copy of a software app to a selected number of known users, which can't simply be copied and given to someone else.

I was thinking of using a digital certificate and nonexportable private key to ensure that only those authorised could run the software, a method which an online bank I know also uses to similar effect.

The software is windows based, .Net etc, but could also call COM components.

Does anyone:

a) know if there are any drawbacks to this method, e.g. is there a way to export 'nonexportable' keys

b) what software components are needed to generate the certificates/keys (without preferably having to set up an internet based cert server), and how they can be validated within the app itself.

Joe

[EddieC]

I have used software from this lot in the past.

www.macrovision.com/solut...index.php3

They used to be called C-Dilla, and are pretty good. I'm not sure if they have an exact fit for your requirments, but you might be able to configure a never ending subsciprtion to the software (which would only work on a licenced machine).