Re: Federal Key Registration Agency

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On Wed, 19 Jun 1996, Igor Chudov wondered:
>Lucky Green wrote:
> At 16:27 6/18/96, TM Peters wrote:
> >Speaking to the Commonwealth Club of California in San Francisco, Reno said
> >her plan would require people to register with the new agency the secret
> >codes -- or "keys" -- they use to encrypt messages online.
> 
>: The cat is out of the bag. Janet Reno is calling for mandatory Government
>: Access to Keys. Not that her statement would surprise anyone on this list.
>: Still, I believe the administration has never before publicly stated that
>: people will be _required_ to deposit their encryption keys with the
>: government. I wonder what the penalties for failure to comply with this
>: requirement will be.
 

> A couple of questions [admittedly, I am not the best expect in American
> politics]: 

> 1) Is there anything real that individual citizens can do?

Keep your PGP262.zip disks in ziplock bags and cache them in the backyard,
forests,The golf courses.  Get a GPS location and escrow the locations with
with trusted friends using Secret Share.  Payout to Jim Bell's AP service.  
Move to Canada?

William Knowles
erehwon@c2.org
Finger for public key




 
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On Thu, 20 Jun 1996, William Knowles wrote:

> Keep your PGP262.zip disks in ziplock bags and cache them in the backyard,
> forests,The golf courses.  Get a GPS location and escrow the locations with
> with trusted friends using Secret Share.  Payout to Jim Bell's AP service.  
> Move to Canada?

As was recently demonstrated by the passage of a "designer drug law" whose
main purpose was to increase jail time for pot, which nobody in Canada had
asked for and was widely opposed, when the US wants Canada to pass a law,
Canada passes that law. If Washington gives us GAK, it's little brother
Ottawa won't be too far behind.

I have seen the text of the speech.  The wire service accounts wildly,
wildly exaggerate.  This is a non-story...except for AG Reno's assertion
that it would take the government a year to break one DES message with a
"supercomputer".  She presumably believes this.  We know the number for
known plaintext attacks, but assuming you don't have a known plaintext,
what's a more reasonable assumption? 

[This message may have been dictated with Dragon Dictate 2.01. 
Please be alert for unintentional word substitutions.]

A. Michael Froomkin        | +1 (305) 284-4285; +1 (305) 284-6506 (fax)
Associate Professor of Law | 
U. Miami School of Law     | froomkin@law.miami.edu
P.O. Box 248087            | http://www.law.miami.edu/~froomkin
Coral Gables, FL 33124 USA | It's hot here.  And humid.

Michael Froomkin writes:
> I have seen the text of the speech.  The wire service accounts wildly,
> wildly exaggerate.  This is a non-story...except for AG Reno's assertion
> that it would take the government a year to break one DES message with a
> "supercomputer".  She presumably believes this.  We know the number for
> known plaintext attacks, but assuming you don't have a known plaintext,
> what's a more reasonable assumption? 

Known plaintext isn't needed for any brute force DES attack. Indeed,
our own Dave Wagner showed in a paper not that long ago how to
automate the process of detecting a good key.

The numbers in the Blaze et al paper are very realistic on this. A
year is total bull -- not even within several orders of magnitude of
accuracy.

Perry

Perry E. Metzger wrote:
> 
> Michael Froomkin writes:
> > I have seen the text of the speech.  The wire service accounts wildly,
> > wildly exaggerate.  This is a non-story...except for AG Reno's assertion
> > that it would take the government a year to break one DES message with a
> > "supercomputer".  She presumably believes this.  We know the number for
> > known plaintext attacks, but assuming you don't have a known plaintext,
> > what's a more reasonable assumption?
> 
> Known plaintext isn't needed for any brute force DES attack. Indeed,
> our own Dave Wagner showed in a paper not that long ago how to
> automate the process of detecting a good key.
> 
> The numbers in the Blaze et al paper are very realistic on this. A
> year is total bull -- not even within several orders of magnitude of
> accuracy.

Further, known plaintext is actually a very reasonable assumption. In 
S/MIME, for example, the first 8-byte block of text is almost certain to 
be 43 6f 6e 74 65 6e 74 2d, (i.e. the string "Content-"). This makes the 
process of analyzing the results trivial.

Raph

At 21:20 -0400 6/20/96, Michael Froomkin wrote:
>[...] AG Reno's assertion
>that it would take the government a year to break one DES message with a
>"supercomputer".  She presumably believes this.  We know the number for
>known plaintext attacks, but assuming you don't have a known plaintext,
>what's a more reasonable assumption?

If the plaintext is ASCII text, the time is the same but the machine is a
little more expensive.  What you do is process 8 or more blocks of
ciphertext in parallel, matching the high order bit of each byte to 0.
With 8 blocks, you get 64 high order bits -- more than the number of key
bits -- so you're not likely to guess wrong.

If the signal is audio instead of text, I don't know what you look for.
That depends on the compression algorithm.

If the signal is compressed text, again I would need to see the comressor
output.

If all you have is one or two blocks of text (e.g., a bank transaction) you
decrypt and decide whether the result is just impossible.  If it's possible
(and there will be many) you send the trial key on to a second processor (a
more general one) to try that key on the whole message to decide if the
message is still possible.

If that processor likes a given key, you send the result to a human -- who
chooses among all the possibles.

In other words, this doesn't have to be one-step-to-success.  All you're
doing is pruning the keyspace to something more manageable.

 - Carl


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|Carl M. Ellison   cme@acm.org     http://www.clark.net/pub/cme          |
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