outer@utcsri.UUCP (Richard Outerbridge) (12/17/86)
From the January 1987 issue of >Home Satellite TV<, "A "CHIP" That Unlocks
Scrambling" by Bob Cooper, Jr. (pp. 51-55, 67):
"The Videocipher has been broken through the U30 device
found inside of the M/A Com descrambler and pictured on
our front cover. It holds the key to a "quick decoding"
fix discovered by many Videocipher hackers. The chip is
re-programmed with user instructions which essentially
unlock the descrambler for transmissions which were
previously secure."
The basic question still remains: Did they break DES or short-cut the keying?
The chip on the front cover is an Intel P27128A-2 L5420254, whatever that
is - EPROM? The article doesn't go into details. It hints that the flaw
was key management ("The decision to transmit the keys, no matter how
cleverly they might be disguised, would later turn out to be a poor
decision.") but devotes a lot of space to talk about "murky" "DES protection
statutes", whatever they are. It also claims that "...military and diplomatic
messages encrypted with DES [are] being distributed all over the globe..."
and echoes the silly M/A-Com treasonability warning. It would seem that
the author doesn't know encryption or the law very well. At one point he
quotes an otherwise unreferenced announcement by NSA:
"Effective 1 January 1986 ... the U.S. government will no longer
sanction the DES code for encryption systems. The DES code has
become vulnerable to code breakers."
Uhh, somehow I don't think that's quite their style...
So: details to follow in the Caribbean. Cooper's Hotline (305-771-0575) says
that attendees will receive sample DEScrambling chip sets as souvenirs!
Humorous note - at one point the article observes:
"It has also been something of a mystery why hundreds of individuals
and groups, working to bust Videocipher, have been allowed to continue
their efforts to bust the system without some form of federal
intervention, or at the very least, a public warning from NSA, the
FBI or the Department of Justice [with reference to the murky DES
protection laws, I guess]. Perhaps, just perhaps, the whole
Videocipher system has been a paper tiger from the beginning."
Sounds like an excerpt from sci.crypt about the DES itself, eh?
--
Richard Outerbridge <outer@utcsri.UUCP> (416) 961-4757
Payload Deliveries: N 43 39'36", W 79 23'42", Elev. 106.47m.john@frog.UUCP (John Woods, Software) (12/24/86)
Two comments on all this: > From the January 1987 issue of >Home Satellite TV<, "A "CHIP" That Unlocks > Scrambling" by Bob Cooper, Jr. (pp. 51-55, 67): > "The Videocipher has been broken through the U30 device > found inside of the M/A Com descrambler and pictured on > our front cover. It holds the key to a "quick decoding" > fix discovered by many Videocipher hackers. The chip is > re-programmed with user instructions which essentially > unlock the descrambler for transmissions which were > previously secure." > >The basic question still remains: Did they break DES or short-cut the keying? I am told that they keys are transmitted encrypted with keys that are shorter than 56 bits (i.e., some of the bits are constant), such that cracking by exhaustive search is practical. > the author doesn't know encryption or the law very well. At one point he > quotes an otherwise unreferenced announcement by NSA: > "Effective 1 January 1986 ... the U.S. government will no longer > sanction the DES code for encryption systems. The DES code has > become vulnerable to code breakers." > Uhh, somehow I don't think that's quite their style... > That doesn't sound like the NSA either, but I know they've said the beaurocratic equivalent. Some time ago, Shamir (I think) demonstrated that DES was untrustworthy by concocting a similar encryption scheme, showing it to people who examined it and decided that it was as secure as DES itself -- then he showed them the trapdoor hidden in the tables. Thus, the belief that DES _can_ have no trapdoor is undermined. -- John Woods, Charles River Data Systems, Framingham MA, (617) 626-1101 ...!decvax!frog!john, ...!mit-eddie!jfw, jfw%mit-ccc@MIT-XX.ARPA Ceci nes pas un .signature. -- Not Quite Magritte
desj@brahms.Berkeley.EDU (David desJardins) (01/09/87)
In article <1207@frog.UUCP> john@frog.UUCP (John Woods, Software) writes: >Some time ago, Shamir (I think) demonstrated that >DES was untrustworthy by concocting a similar encryption scheme, showing it >to people who examined it and decided that it was as secure as DES itself -- >then he showed them the trapdoor hidden in the tables. Thus, the belief that >DES _can_ have no trapdoor is undermined. This is, I believe, false. It is true that many people have tried to do this, but no such successful effort has been reported. -- David desJardins
henry@utzoo.UUCP (Henry Spencer) (01/11/87)
> >Some time ago, Shamir (I think) demonstrated that > >DES was untrustworthy by concocting a similar encryption scheme... > >then he showed ... the trapdoor hidden in the tables. Thus, the belief that > >DES _can_ have no trapdoor is undermined. > > This is, I believe, false. It is true that many people have tried to do > this, but no such successful effort has been reported. The statement is true despite the lack of success in finding a DES trapdoor. Read the original comment carefully, please: the question is not whether DES has a trapdoor -- nobody except, possibly, NSA knows -- but whether it *could plausibly* have a trapdoor. The construction of a superficially- secure DES-like system with a hard-to-find trapdoor demonstrates that such systems can have trapdoors that are difficult to find. Combined with the continuing unwillingness of NSA to permit disclosure of the design principles underlying parts of DES, it's not proof but it is suspicious. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,decvax,pyramid}!utzoo!henry
henry@utzoo.UUCP (Henry Spencer) (01/12/87)
Apologies to David, I must have been half asleep when I posted my previous
article. I missed his point (and can only plead that I think he could have
phrased it better...), which was that apparently nobody HAS yet come up with
a strong-looking trapdoor-equipped DES-like system. The attempt has been
made but without success; they've all been fairly weak.
--
Henry Spencer @ U of Toronto Zoology
{allegra,ihnp4,decvax,pyramid}!utzoo!henry