Re: Simplest Dongle Method? Making a file uncopyable on CD?
Re: Simplest Dongle Method? Making a file uncopyable on CD?
- Subject: Re: Simplest Dongle Method? Making a file uncopyable on CD?
- From: Nicko van Someren <email@hidden>
- Date: Tue, 27 Jun 2006 16:41:29 +0100
On 27 Jun 2006, at 00:33, Scott Ribe wrote:
Most of our customers are
'power' users in broadcast and film, very honest, and the
majority acquire latest HW/SW upgrades on a very regular basis.
So then, why waste your time and inconvenience your users?
Absolutely. As mentioned elsewhere, bits are inherently copyable.
There are some fairly effective copy protection systems which
basically encrypt the majority of the application and decrypt it on
the fly using a key held in a USB dongle, but if your users are
mostly honest and mostly want to run up to date versions of the
application then I would hazard that your biggest risk is going to be
people running multiple copies across an office.
There have been endless threads on this list about copy protection
and how to make license keys. My favourite is to use digitally
signed messages using public key crypto but you should look on the
archives for details. I will however add one thing:
Since OS X 10.2 Apple have made it very easy to advertise network
services using Bonjour and discover what services are on your local
network. Basically you create an NSNetService with suitable name and
then you can use an NSNetServiceBrowser to look for what's out there
and its delegate gets informed when services are found. This
actually provides a very simple and fairly effective way to limit the
number of copies of your program that can be run on a _local_
network. All you do is advertise a net service that allows the
serial number of your program to be read remotely and have your
program also look for all instances of that service, read the serial
numbers of the other copies of the program and complain to the user
if there are too many copies of the same serial number. While in no
way infallible it's very simple to implement and it will in most
cases cover the scenario of your professional 'power' users having
one licensed copy for which they receive regular updates and which
they then run on multiple machines around the office.
Cheers,
Nicko
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