Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!cwjcc!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: sci.electronics
Subject: Re: advice on descrambler
Summary: vcII not all taht secure
Message-ID: <1670@neoucom.UUCP>
Date: 30 Jun 89 14:20:56 GMT
References: <111377@sun.Eng.Sun.COM> <680@lopez.UUCP> <120@raider.MFEE.TN.US>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 40


Unfortunately, the Videocipher II is not a terribly secure system,
eventhough it uses the DES algorithm to encode the digital audio
stream.  The problem lies in the fact that the key updating is done
via the over-the-air data stream.

I don't know the specifics of the methods used to attempt to
compromise videociphers, but I've heard that pirates modify the ROM
controlling the housekeeping CPU (an 8048).  It is possible to
spoof the audio subsystem by sending it bogus control messages from
the CPU, then trapping key updates illegally.

After General Instruments bought the Videocipher business from
MA/Com, there was a mass recall of the original vcIIs, where GI put
in new motherboards that had green epoxy dumped all over the
vulnerable parts of the board (ROM, CPU, slave CPU for the audio
subsystem, etc.) to discourage unauthorized modifications for
reception.  The latest vcIIs apparently are using macrocell ASICs
that do away with the separate ROM chip, as enterprising prirates
were still grinding off the epoxy to change the ROMs.

I do say illeagally.  There are heavy fines and/or jail in the US
for theft of service.

A new vcII+ has been announced that will make use of key cards
that are distributed via surface mail, which is what they should
have done all along.  More "tier" bits will be added too, which
will allow more scrambled services to be supported.  In the current
vc technology, all the available tier bits have already been sold
to various broadcasters, thus preventing any new separate services
from being added.  The new vcII+ is also rumored to be desinged
such that it will be able to support high definition TV in the
future.  Exactly how the new vcII+ is going to affect the market is
unclear, as there are a lot of the older model in the field that
should need continued support.  It would be very unkind for GI to
welch on its promise to the US government that the original vcII
would be the only encoding system the world would ever need.

Bill
wtm@neoucom.UUCP