Licensing and restriction are tied together, If I write a Perl program and
license it to a client and he cannot easily copy or pass it on to a third
party then I can continue to profit from my work. If the source is available
he can pass it on to any third party who does not have to pay a licence fee
to me. Restriction allows me to control this and hopefully continue to
program. The question is how difficult I have to make this to stop most
illicit use of my work. There has to be a middle way between all source
being secret and some confidentiality. If someone is going to use my work to
make money then I should have a right to secure some of this.
-----Original Message-----
From: Abdulaziz Ghuloum <[EMAIL PROTECTED]>
To: Robin Lavallee (LMC) <[EMAIL PROTECTED]>; [EMAIL PROTECTED]
<[EMAIL PROTECTED]>
Date: 02 June 2001 17:12
Subject: Fw: Re: Licensing
>Hello
>
>It seems like you got two issues mixed up slightly. One is the licensing
issue
>and the other is the restriction issue. Let me elaborate:
>
>Licensing is an agreement between the program supplier and the user
regarding
>the use of the program, redistribution restrictions, the freedom to modify,
...
>
>You can adopt the licensing agreement most suitable to your needs from many
>licensing schemes already available. Probably by looking at the license
>agreement of any shareware application, you will get an idea of how it's
done
>to limit the number of days the user may use the program before paying or
>removing the program. This is the same whether the program is written in
C,
>Java, Perl, VB, or any language. Users are expected to obey the license.
>
>Now if you want to force your users to obey the license, you get into
trouble.
>First, assume you can force your users to use the program for n-days, then
you
>would not even need to supply any other restrictions in your license.
>
>Can you, using your program, *force* your users to obey the license. You
>already answered by saying that users can simply comment out the check
point.
>BTW, this is not a perl limitation. There exists many decompilers in the
>market for decompiling JAVA, VB, and even C compiled binaries. The quality
of
>these decompilers differ greatly, but bad decompilers can be thought of as
>giving obfuscated code of the same program. Obfuscation does not help
since it
>assumes no one (or program) would be smart enough to reverse it.
>
>I believe perl compilers come in two flavors: one that actually maps every
perl
>statement into the appropriate C statement making a C program that is
>equivalent to the Perl program, then compiling the C program. The other
type
>of compilers translates your program into perl OP-Code which is faster to
load
>(the parsing step is mostly eliminated). Since the two programs (yours and
the
>compiled one) are equivalent, the compiled version can be reversed back to
a
>different version of your program. The check points can be then removed.
>
>I believe the compiled perl programs are harder to crack, because of the
use of
>translation to the C program which is practically unreadable, and then the
use
>of optimized C compilers which produce binaries that are hard to map back
to
>the appropriate C functions. VB programs contain almost an explicit
version of
>the VB source code making the decompilation into an intelligible program
easy.
>For JAVA, look at the JAVA-Decompilers-HOWTO.
>
>So, the bottom line is, you cannot have a 100% safe way of preventing your
>users from removing any check point. (I live in a third world country
where
>you can get a fully functional version of AutoCAD or 3D-Studio for 5 USD,
and
>the original version of these software come with hardware dongle)
>
>
>There is another issue that I would like to leave open which is: Some perl
>compilers compile all modules used by the program in order to eliminate
module
>dependencies. Your program comes as one file that runs without requiring
such
>and such modules. How would this influence your licensing agreement? Does
>your program need to be GPLed if it `use`s a GPLed module?
>
>
>
>
>
>On Fri, 1 Jun 2001 11:28:47 -0400 , Robin Lavallee (LMC) said:
>> Hi people,
>>
>> Has anyone been able to conceive some kind of licencing scheme in
>> Perl ?
>> That is, I want to deploy a Perl program that the customer will only be
>> able to
>> use for 30-60-90-30n days. This causes great problem to implement in
Perl
>> since
>> the customer could simply comment-out the line that does the check (no
>> matter
>> what kind of check that is). I could use obsufucation technique, but
that
>> seems annoying. Anyone has a suggestion ?
>>
>> -Robin
>>
>
>
>
>
>
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