[Tutor] Obssfurcatedpuytthonlessons nneeded

Alan Gauld alan.gauld at btinternet.com
Sun Jan 20 09:38:31 CET 2008

"Kirk Bailey" <deliberatus at verizon.net> wrote

>I  aam  writing some software which calls for some  unreadable code 
> it to let me secretly  set a registration key- it is to be 
> shareware.

You don;t need to use a registration key for shareware.
Other much easier options are:
1) Rely on the honesty of your users.
2) Provide good quality documentation in pa[per only
format to buyers

Of course nothing is foolproof and whatever you do will be
hacked and free copies will become available so ultimately
you will always rely on honesty. That is the nature of

> I know this can be done, but have not the foggiest clue of how todo 
> it.

There are lots of options, some dont even require you to
distribute a key since the key can be an encrypted form of
the users email address or user name (which is usually
obtainable via an environent variable...). Another option
is to use the checksum of the file itself, or the MAC id
of the computer.

Another option is to have an open key in the distribution and
your web site generate a secondary key based on the open
key and the users download credentials (a sequence number
and time usually). This is somewhat similar to public key
encryption protocols like RSA...

But there are many ways to do it which do not involve
writing obscure code which is probably the least secure
technique. But ultimately they can all be bypassed its
only a matter of time and effort..

Alan Gauld
Author of the Learn to Program web site

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