From: Bill Stewart <stewarts@ix.netcom.com>
Date: Sat, 23 Sep 95 15:54:15 PDT
To: cypherpunks@toad.com
Subject: Re: The Fortezza random number generator is not trustworthy
Message-ID: <199509232254.PAA11243@ix8.ix.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


A nice addition to any Netscape RNG hacks is the comment that,
while Netscape may have a bug in their RNG, it's detectable and fixable;
the NSA may have a BUG in theirs, and only they'll know for sure...

>> Yes Fortezza cards can be instructed to produce a random number through one
>> of its library calls (someday they'll have a real API).  One of the
>> diagnostic tools I had tested this function.  What algorithm do they use?
>> Haven't a clue.  Sources say that the RNG implementation may vary from vendor
>> to vendor (i.e., GTC, Spyrus, Mykotronix, etc.).

John Gilmore's comments on CAPSTONE, subliminal channels, and FOIA blackouts 
certainly add depth to this suspiciousness.  I'd initially not been too worried
about the Fortezza (besides the obvious Master Key problems) because the NSA
is letting the military use them for Defense Messaging Service.  However,
if the RNG might be different for different vendors, the non-military versions
may be using a weak RNG, which the NSA has a backdoor to.  Alternatively,
the RNGs may all be the same, but there may be an option that the military can
use to get full-strength random numbers while the public, not knowing this,
gets weakened ones (e.g. the first n bits of the RNG may be random, and the next
N-n bits may be a strong hash, while there are N-n real random bits in another
register if you ask for them nicely.)

On a technical note, I would have thought that Fortezza and/or CAPSTONE used
some sort of hardware RNG, i.e. noisy Zener diodes or whatever.  I've seen it
mentioned on this list that some other NSA secure phones, such as STU-III,
do that.
#---
# Bill Stewart, Freelance Information Architect, stewarts@ix.netcom.com
# Phone +1-510-247-0664 Pager/Voicemail 1-408-787-1281
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