Re: TIS--Building in Big Brother for a Better Tommorrow

At 12:02 AM 2/23/96 -0800, Bill Frantz wrote:
>At 11:16 PM 2/22/96 -0800, Timothy C. May wrote:
>>And we should all remember, again, that basic observation: even if "key
>>escrow" is needed to recover *stored* files, it sure ain't needed for
>>*communications*!!
>
>If a key is being generated for two way communications, then it should be
>generated via a protocol like Diffie-Hellman which leaves no recoverable
>knowlege of the key outside the participants, and discarded when the
>session is over of frequently, whichever occurs more often.  This procedure
>will reduce the incentive for rubber hose attacks to recover these keys.

I noted long ago that one disadvantage with having a single, standardized 
encryption chip (like Clipper, even with the key-escrow un-enabled) is that 
the NSA has plenty of money in its budget to build a fake chip that can be 
installed during a black-bag job.  True, if they could fake one chip they 
could fake 10, but it's harder to do and the demand for any single kind of 
chip might drop to one per year.   Unfortunately, a sufficiently-complex 
FPLD would probably sub for anything if it were in the right package...

Faking crypto chips for public algorithims is theoretically
more difficult, because its simple to create a DES_verify routine to make
sure your DES chip is working right.  Its more difficult to
near-impossible if the chip picks the key, as it must to avoid easy
rouge implementations.

	If the rouge implementation can choose a key, then it can
pre-calculate the appropriate checksum, and then simply tell the other
unit "We're going to use this key."  Thus, keys need to be chosen by
the chip, making it tough to see if the chip is functioning properly.
I suspect the NSA knew this.

	For more on rouges, see Matt Blaze's paper, on
ftp.research.att.com/dist/mab/keyescrow or somesuch.

jim bell wrote:

| I noted long ago that one disadvantage with having a single, standardized 
| encryption chip (like Clipper, even with the key-escrow un-enabled) is that 
| the NSA has plenty of money in its budget to build a fake chip that can be 
| installed during a black-bag job.  True, if they could fake one chip they 
| could fake 10, but it's harder to do and the demand for any single kind of 
| chip might drop to one per year.   Unfortunately, a sufficiently-complex 
| FPLD would probably sub for anything if it were in the right package...
| 


-- 
"It is seldom that liberty of any kind is lost all at once."
					               -Hume