Re: Aw: Re: [stella] Is Stella GPL'd? (was StellaX PAL detection)

Subject: Re: Aw: Re: [stella] Is Stella GPL'd? (was StellaX PAL detection)
From: Julian Squires <tek@xxxxxxx>
Date: Fri, 1 Feb 2002 10:59:50 -0330
On Fri, Feb 01, 2002 at 10:30:43AM +0100, cybergoth@xxxxxxxx wrote:
> So? I could make Stella read somewhat strange packed 
> BINs instead or something like PGP it.
> Then one could release the complete source of the thing
> but only emulators compiled with a certain key are able 
> able to decrypt the ROMs that are encrypted with the 
> same key. 
> Ha! That's even better! Everybody can encrypt his 
> own ROMS and emulator and no-one can debug them 
> out, even when the source is available :-)

Ah, but that's just what they did with DVDs, and it was trivially
broken. (Actually, the hard part was getting the DeCSS algorithm,
the easy part was getting a key from one of the ``licensed''

The only way to provide provable copy protection in this way is to
have your ROMs encrypted (with a respectable encryption algorithm),
and to provide the encryption key only to legitimate users who are
not going to distribute their keys -- and accept the fact that these
users could reverse engineer your program.

As soon as someone who plans on modifying your program obtains one of
the keys, whether it's embedded in an emulator or distributed only
to legitimate users, they can, with enough work, reverse engineer your
program. I will admit, though, that of course more ``practical''
schemes will still foil 99% of pirates and what-have-you, but it is
that 1% (who would do it, no doubt, just to prove you wrong), who are

While no real surprise, an article about copy protection in a modern
playstation game is at
and is worth reading just because it shows that you don't need
_perfect_ copy protection (which is inconvenient), just pretty
good copy protection.

 |/|  Julian Squires <tek@xxxxxxx>
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