From: tcmay@netcom.com (Timothy C. May)
Date: Tue, 26 Jan 93 10:31:31 PST
To: cypherpunks@toad.com
Subject: Re: Computerized OTP (was 5th AMENDMENT & DECRYPTION)
In-Reply-To: <m0nGtQQ-000jp9C@phantom.com>
Message-ID: <9301261828.AA25565@netcom3.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


Murdering Thug (not his real name) writes, quoting me:

> > With strong crypto, e.g., with 300 decimal digit moduli, the "costs"
> > of decryption by brute force could easily exceed the GNP/GDP of the
> > U.S.
> 
> Since none of us have ever been inside the NSA, we cannot underestimate
> their power and resources.  For all we know they may have 500 Intel Delta
> supercomputers linked together, each having 65,536 i860-XP/50mhz chips.
> We really don't know what kind of iron they possess.  Thus we can't assume
> that they can't factor extremely large numbers easily.

Doubtful. That's why I cited 300 decimal digit moduli...the current
factoring record is, I believe, a 105 digit number, and this took a
network of Sun workstations a year or so (this was big news some
months back). As a former Intel employee and current Intel stockholder
(yeah!), I certainly hope the NSA is consuming large numbers of
Touchstone Deltas, but they won't do much good against strong crypto.

A bigger effect would be a breakthrough in factoring. No evidence of
this, though. 

> The only way to thwart the NSA is to use an encryption scheme which has
> been _proven_ uncrackable.  The only one I know of is the One Time Pad.
> A person I know is working on a computerized version of the OTP that
....rest elided...

Sure, one-time pads are information-theoretically secure.

The problem is the key distribution problem, as well as the storage of
one-time pads. For example, for the couple of hundred folks on this
list to communicate securely will other members, each would have to
meet in person or deliver by trusted courier a one-time pad to _each_
of the others! A very tough logistical problem, fraught with potential
weaknesses, and much easier to spoof or break than, for example,
factoring very large numbers.

This is the problem, the key distribution problem, that public key
methods solve.

-Tim


-- 
..........................................................................
Timothy C. May         | Crypto Anarchy: encryption, digital money,  
tcmay@netcom.com       | anonymous networks, digital pseudonyms, zero
408-688-5409           | knowledge, reputations, information markets, 
W.A.S.T.E.: Aptos, CA  | black markets, collapse of governments.
Higher Power: 2^756839 | Public Key: waiting for the dust to settle.