🚀 go-pugleaf

In article <18742@ucbvax.BERKELEY.EDU> rotondo@ernie.Berkeley.EDU.UUCP (Scott Rotondo) writes:
>The main thing that NSA knows is the way in which the S-box numbers were
>derived.  There has been speculation without proof that there is a trap
>door here to allow the NSA to crack it.  There has also been speculation
>that the NSA cannot crack DES, and that is why they are pushing for a new
>standard where they control the keys and the algorithm.

Although I haven't studied DES very hard and don't have any inside
(i.e. classified) information about DES, from a previous life as a
part-time cryppy I don't see how DES could be considered unbreakable,
in the absence of sufficiently frequent key changes.  This follows
from very general information-theoretical considerations.  Because of
the complexity of the encryption algorithm, the unicity distance is
probably rather large, but it wouldn't be infinite.  On the other
hand, it is probable that it would take knowledge that only NSA and
similar organizations tend to have to routinely break DES using
economically feasible expenditure of resources.  Since I have to be
careful not to discuss anything about this subject for which I can't
point to publicly-available descriptions, suffice it to say that the
articles I've seen on cryptography in the open literature don't hold
a candle to the ones I used to read in the NSA Technical Journal.  I
would bet that NSA can break DES any time they so choose, if they
have a large enough contiguous sample of the cipher stream; "trap
doors" shouldn't be necessary.

The newer proposal for general government encryption amounts to a
reversion to the military way of doing business; they have always
classified both the keys and encryption system details
(algorithms).  Even though it's taken for granted in the cryppy
business that the "opposition" sooner or later determines the
details of the encryption system, it still makes sense to try to
delay their doing so.  The keys of course must be protected.
(So-called "public key" systems attempt to make the latter
unnecessary, but I wouldn't place reliance on the opposition's
lack of sufficient cleverness or dumb luck to protect anything of
very great value.)

Consider this:  If NSA can really design a truly secure system
for government use, then they sure as hell wouldn't want everyone
whose traffic they read to learn how to do the same.  It is
perfectly natural that no details of how critical aspects of a
secure cryptosystem are determined are made public.  (Personally
I would love for there to be a universally-used secure system,
since I value privacy.  But virtually no government operates on
such abstract considerations; rather they attempt to attain
short-range advantage over other governments as expeditiously as
possible.  I wish ours were different, and think it once was.)

In summary, I don't think there is a conspiracy on NSA's part,
and I estimate NSA's capabilities to be higher than other people
seem to think.  (I suspect NSA is happy to be underestimated.)