kencr@haddock.ima.isc.com (Kenny Crudup) (06/29/89)
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! A place I used to work for used to have EPROMS that would go in VCII modules in Tracker Systems home units that replaced the original code, and would first lock in, and then continue to recieve programming. -- Kenneth R. Crudup, Contractor, Interactive Systems, Cambridge MA StarTrekV 3'rd favorite line: "Oh yeah?! Beam THIS up, pal!!" - D. Letterman E-Mail, (which tends not to be delivered :-( ) Phone (617) 661 7474 x238 {encore, harvard, spdcc, think}!ima!haddock!kencr kencr@haddock.ima.isc.com
crc@raider.MFEE.TN.US (Charles Cain) (07/01/89)
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!!!!!!-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-