I have heard of a commercial product sold in the UK called a PICBuster,
and I have seen a suggested attack method on the 16C84 which is alleged
to work (it also sounded likely to fry the chip, though) - search on
AltaVista for 16C84 and code and protect, I think.

The interest in Europe regarding PIC code protection defeating is
largely due to the use of these chips in satellite scrambling systems.
There is a thriving black market in smartcards which defeat the
encryption systems. Why they bother, I can't imagine. Its only 500
channels of utter crap, anyway, but that's human nature for you.....
What these minds could do in solving the world's *real* problems (sigh!)

> ----------
> From:         Pete Klammer[SMTP:pklammer@RACOM.COM]
> Reply To:     pic microcontroller discussion list
> Sent:         Wednesday, December 17, 1997 6:31 AM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: CODE SECURE WITH PIC?
>
> Terviist!
>
> please, can you be more specific?
>
> Can you tell me who offers such services, or how to find them?
>
> I don't doubt the technical feasibility of this, but as it is
> presented
> so far,
> it sounds like one of those "urban legends" (you know: the story about
> the dog
> in the closet choking on the burglar's finger it had bitten off, or
> whatever that was...)
>
> I would like to know how much it really costs and how long it really
> takes,
> and what the success rate is (do you need a number of parts to ensure
> full ROM reconstruction),
> is it a destructive process (can you sneak the cracked part back into
> service?).
>
> And then I would like to hear these guys discuss what methods are
> better, more expensive, etc.
>
> Peter F. Klammer / pklammer@racom.com
> Racom Systems, Inc. / 6080 Greenwood Plaza Blvd. / Englewood, CO 80111
> (303)773-7411 / FAX:(303)771-4708 / http://www.racom.com
> World's First Dual-Interface Symmetric-Access FRAM Smartcard
>
> > ----------
> > From:         Alexey Vladimirov[SMTP:avlad@MAILBOX.RIGA.LV]
> > Reply To:     pic microcontroller discussion list
> > Sent:         Tuesday, December 16, 1997 7:36 AM
> > To:   PICLIST@MITVMA.MIT.EDU
> > Subject:      CODE SECURE WITH PIC?
> >
> > 15 Dec 97, zhuxh@cheerful.com writes to All:
> >
> >  z> I am woundering if the code protection with PIC's is as secure
> as
> >  z> promised by Microchip?
> >
> > Yes, due to Microchip promise only, that code protection exists, and
> > nothing
> > about actual strength of code protection.
> >
> >  z> as far as I know, there is a company in Beijin that offers
> service
> > to
> >  z> help decode the Microchip's PICs. The cost is about US$1000 for
> > each
> >  z> chip!
> >
> > The same service you can also found in Moskow, Russia. They promise
> > any
> > protected PIC code reverse engineering with cost lower, than $1000
> > (same price!) in one-two days. For PIC16C84 it can be done for
> almost
> > free and
> > for PIC16F8x price is lower, than $100. Probably, both companies use
> > some
> > technological backdoors in Microchip products. Sorry, I don't know
> any
> > technical details, only see advertisiments and know some cases of
> the
> > successfull using of this service.
> >
> >  z> I am afriad my own coding with PICs will be copied by others one
> > day.
> >  z> Do you have any idea on this? Is my worry unnecessary?
> >
> > The only things, that can protect you - change you product as
> > frequently, as
> > possible, add new features, new ideas and didn't try to obtain
> > superprofit.
> > If you need really protected product for security applications - use
> > special
> > security designed chips, not wide available microcontrollers.
> >
> > Alexey
> >
> > --- GoldED/2 2.50+
> >
>