Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!bionet!ames!killer!mjbtn!raider!crc
From: crc@raider.MFEE.TN.US (Charles Cain)
Newsgroups: sci.electronics
Subject: Re: VCII
Message-ID: <121@raider.MFEE.TN.US>
Date: 30 Jun 89 21:04:11 GMT
References: <111377@sun.Eng.Sun.COM> <680@lopez.UUCP> <120@raider.MFEE.TN.US> <13877@haddock.ima.isc.com>
Reply-To: crc@raider.UUCP (Charles Cain)
Distribution: na
Organization: RaiderNet Public Access, Murfreesboro, TN
Lines: 28

In article <13877@haddock.ima.isc.com> kencr@haddock.ima.isc.com (Kenny Crudup) writes:
>In article <120@raider.MFEE.TN.US> crc@raider.UUCP (Charles Cain) says:
>>If someone is lucky enough to guess the 56 bit key, then he might think he has
>>the system beat. Not quite. There are 2 modes of operation, fixed key and 
>>individually addressable. Fixed key is used mostly during testing. When the
>>system is fully operational, IA is used. Each uplink site that is transmitting
>>scrambled material has a computer that transmits the next months key and the
>>address of those descramblers authorized to receive the program. The computer
>>is capable of authorizing or deauthorizing up to 2.5M descramblers a day.
>
>Well, it seems they give you the stuff you need right there! I assume that
>of course you would need to know the key at least once, but after that, hey!

The only flaw that I see with that logic is that in the standard for the DES
algorithm, using a 56 bit key gives you a little bit over 72 MILLION to 1
odds against finding the right key. Then, all the earth station has to do
is change the key. I don't know all the particulars about the keys but I do
know that each earth station cannot use the same keys at the same time. So
although it may look simple on paper, in reality it would seem it is a little
"bit" more difficult. :-)

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
DOMAIN: crc@raider.mfee.tn.us     |	      From NASHVILLE, TENNESSEE     
Satellite Engineer, TNN           |           Home of the Grand Old Opry!
PHONE:  (615-459-9449)            |                             
-----------------------------------------------------------------------------
Disclaimer: These words do not reflect or express the views of The Nashville
Network in any way. The words and the way they are used is solely MY FAULT!!!!!!-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-