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From: rob@uokmax.ecn.uoknor.edu (Robert K Shull)
Newsgroups: comp.sys.mac.programmer,comp.protocols.appletalk
Subject: Re: Idea for painless copy protection
Message-ID: <1991Jan29.232157.20917@uokmax.ecn.uoknor.edu>
Date: 29 Jan 91 23:21:57 GMT
References: <1991Jan27.144523.20674@phri.nyu.edu>
Organization: Engineering Computer Network, University of Oklahoma, Norman, OK
Lines: 61

In article <1991Jan27.144523.20674@phri.nyu.edu> roy@alanine.phri.nyu.edu (Roy Smith) writes:
>
>	When the program starts up, it installs something which listens for
>broadcast packets to a specific port (my knowledge of appletalk is sketchy,
>but this is easy to do in IP and I'm assuming AT has some similar
>mechanism).  The program then sends out a broadcast packet to that port and
>listens for any responses.  The responses it would get back would contain
>the serial number of other copies of the program installed elsewhere on the
>same AT network.  If any S/N matched that of this copy, it would refuse to
>run.
>
>	Let's not get into a philosophical debate about the ethics of
>pirating and/or selling software, I'm just looking for comments on the
>technical issues.  First, would it work?  Obviously, people could use

This would undoubtedly work (there are already some commercial packages
that use this scheme). It does, however, have a major drawback for some
settings. We have about 25 machines running software from a central server.
We run a software package called LaunchBreak which limits the number of
copies of a program in use to a fixed number (set by us). We set this number
to be equal to the number of copies which we legally own.
If a scheme such as you propose is used, we then have a problem. We can
(1) scatter a number of copies of software onto different machines,
and put up signs telling which machines can be used for which applications
(ugly), (2) put multiple copies of the software onto the server, along with
some kind of front end to pick one that's not currenltly in use (more code
to maintain), or (3) hope that the software company makes a "network version"
which will work from our server (so much for the Mac and "integrated
networking") and without deciding we should pay a fortune for it.


Also, LaunchBreak alters the application so that copies which are removed
from the system won't function, so we get automatic copy protection for
the software we use.
If we put the software on the individual machines, everyone can immediately
make copies of it to take home.
So, in our case, this kind of copy protection actually means that more people
will illegally copy the software, since there would be no way to prevent it.

Our policy so far has been to avoid software which uses this method of copy
protection, unless it is requested as a "must have" package (which hasn't
happened yet).

By the way, there are few things as irritating as discovering that you've
got the wrong one of a set of 10 identical, unnumbered disks (thanks, TOPS).
Doesn't exactly make one enjoy using the product.

>with Responder, would it?  It would only happen once per launch, so I would
>guess that would minimize the damage.

If you don't check continuously, there is a trivial way to defeat the
protection. Pull the plug on the AppleTalk line until the program starts up,
then plug it right back in. If you check continuously while the program is
running, then you might end up loading the network (especially on slow
LocalTalk networks).
	Robert
>Roy Smith, Public Health Research Institute

-- 
Robert K. Shull
rob@uokmax.ecn.uoknor.edu				chinet!uokmax!rob