Here is a disturbing thought.

Now, we no longer live in the days of big filing cabinets. We live in
the electronic age. I asked myself, how big could the escrow database
get? How hard might it be to steal the whole thing, particularly were
I an NSA official operating with the tacit permission of the escrow
houses? (We can pretend that such will not happen, but thats naive.)

Well, lets see. Ten bytes of each escrow half. Lets asume ten bytes of
serial number -- in fact, I believe the serial number is smaller, but
this is an order of magnitude calculation. We assume 250*10^6 as the
population, and that each person has a key. I get five gigabytes for
each of the two escrow databases. Fits conveniently on a single very
valuable Exabyte tape. This can only get easier with time, but who
cares -- I can already hold all the clipper keys in the country in my
pocket on two 8mm tapes.

Admittely, they will think of safeguards. They won't put the whole
database on one disk, prehaps. Maybe they will throw stumbling blocks
in the way. This changes nothing -- they keys will be needed every day
by hundreds if not thousands of law enforcement types, so convenience
will dictate that the system permit quick electronic retrieval. At
some point, with or without collusion by the agencies, those exabyte
tapes are going to get cut. Dorothy Denning and David Sternlight will
doubtless claim this can't happen -- but we know that "can't" is a
prayer, not a word that in this instance connotes realism.

With two exabyte tapes in your pocket, you would hold the keys for
every person's conversations in the country in your hands. Yeah, you
need the "master key" two -- but thats just ten bytes of information
that have to be stored an awful lot of places.

Come to think of it, even if the NSA getting a copy of the database
isn't a threat to you because unlike me you have no contraversial
political views, consider foreign intelligence services. You know, the
ones that David Sternlight wants to protect us from because of the
evil industrial espionage that they do. The French apparently do have
a big spying operation in friendly countries to get industrial
secrets, so he isn't being completely irrational here (although why
our companies couldn't use cryptosystems without back doors is left
unexplained by those that point out this threat.) 

Presumably, foreign intelligence services can get moles into the NSA
and other agencies. We have proof by example of this: its happened
many times. Presumably, someday they will get their hands on some
fraction of the keys. You can't avoid that sort of thing.

Don't pretend that no one unauthorized will ever get their hands on
the escrow databases.

We crypto types are all taught something very important at the
beginning of intro to cryptography -- security must depend on the
easily changed key that you pick to run your system, and not on a
secret. The escrow databases aren't the sorts of secrets that our
teachers told us about, but they are the sort of big secrets they
would lump into this category. Imagine trying to replace 100 million
Clipper chips.

I cannot believe that the NSA or whomever it is thats doing this
doesn't realize all this already. They are too smart. There are too
many of them who have made their bones in the real world. I suspect
that they know precisely what they are doing -- and that what they are
doing is giving us the appearance of safety so that they can continue
to surveil in spite of the growth of strong cryptography. I suspect
that they realize that they can't put things off forever, but they can
try to delay things as long as possible.

Who knows. Maybe even some of the higher ups, the inevitable
bureaucratic types that rise in any organization, really do believe
that this scheme might give people some security, even as their
subordinates in Fort Meade wring their hands over the foolishness of
it all.

--
Perry Metzger		pmetzger@shearson.com