Re: Licences 101 - Copy Protection for Newbies
Re: Licences 101 - Copy Protection for Newbies
- Subject: Re: Licences 101 - Copy Protection for Newbies
- From: "Steven M.Palm" <email@hidden>
- Date: Mon, 23 Sep 2002 08:57:47 -0500
On Monday, September 23, 2002, at 08:26 AM, Jeremy Dronfield wrote:
2. App compares the entered value with a valid value (or array of
valid values) held internally. If it gets a match, then:
I would suggest instead some algorithm be implemented to generate keys
which match a given validation formula/checksum/whatever. This would
allow you to know if you have a key that is "supposed to be" valid,
although not necessarily matched against a list of keys you have
supplied.
The downside to a master list is that people who get the application
before you assign them a key cannot have it in their app, and so
therefore you'd have to send them a new version, which is a slight
inconvenience.
The downside of this approach is that it allows for the potential of
someone figuring out your algorithm, and then making a key generator
from which they can produce as many "valid" keys as they want.
One interesting approach I've seen and quite like is to factor the
date into the key somehow, so that a given key is only valid for
activation for a period of time, based on when it was generated. This
is more difficult, but couple this with some hashing against a hardware
value to store a disk file key for future checking "are we legal"
during program runs, and you have something that might slow down the
serial posters, and defeat the ability to pass around the disk license
file from machine to machine.
4. App triggers an email message to developer registering the
transaction.
I personally don't like this. Not because I'm doing anything illegal,
but I simply abhor the idea of software doing something (especially
communicating with the outside world) without my invocation. Yes, I
suppose I would be shocked to know what really goes on in a lot of
apps... ;-)
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- Steven M. Palm
- Ham Radio Call: N9YTY
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