Re: RSA - Public vs. Private Keys

William Stacey [MVP] wrote:
1) Your server side creates a license (xml, csv, etc) and signs it
with private key. Optionally, your client will send a unique machine
hash to the server first, so that your license can be tied to *that
machine only - otherwise that license will work on any machine.

Note that "that machine only" is a changing quantity. My motherboard breaks
tomorrow - have I lost the ability to use your application through no fault
of my own, even if I replace my motherboard? You have to consider the
support burden - and ill-will from the customer - this solution causes.

This does work. However, it still does not protect your app. If
your app is on a client, you can Not protect it. It can be cracked
or changed to get around all that fancy encryption. If you still
want that, there are free and paid solutions already that do the
above.

And they still suffer from the same problem - anyone with sufficient skill
can pretend to be the computer, and supply information to the signature
verification, or other process.

The next step up is a hardware key - a "dongle" - that will allow you to
restrict your software to running only with the approved dongle. Then you
have to handle the support effort of verifying customers whose dongles have
been lost or damaged, and suddenly can't use their software.

Alun.
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