Re: Controlling licensed software?

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Quoting Matisse Enzer <matisse@xxxxxxx.xxx>:

> This sounds like avery workable solution. CPAN is so wonderful :-)

Ok, but beware...

The effectiveness of any software licensing scheme depends entirely on 
the skill
of the hackers you are trying to stop.  For instance, to prevent a novice perl
coder from modifying your code, the Crypt::License module may indeed be all
that is needed.  Note however that all you are doing by using 
Crypt::License is
moving the weakest link from your source code to the Crypt::License module
(which is still just pure-perl).  A knowledgable perl hacker could reproduce
the original source code for your program just by adding a few lines to the
Crypt::License module in the right place.

By the same token, you could go to the trouble of compiling C libraries in an
attempt to secure your code, only to have a knowledgable hacker dissassemble
your program and noop your license checks.

As long as you are handing over your software, there's no fool-proof licensing
scheme.  The main goal should be to make it difficult enough to circumvent so
that it isn't worth the effort for most customers.  For most vendors this
usually means combining at least two or three different obfuscation 
mechanisms.

With that said, I'd still personally prefer to host the application and charge
ongoing service fees.

my $.02
Tony

> On Sun, 20 Feb 2005, Adi Fairbank wrote:
>
>> Take a look at Crypt::License on CPAN.  I used it a couple years back to do
>> exactly what you are trying to do.  It encrypts your Perl source 
>> code and then
>> decrypts it on the fly.  There is a slight overhead for the 
>> decryption, but if
>> running under mod_perl, that should be negligible since it would 
>> only need to
>> decrypt on apache startup.
>
>