*BSD News Article 63308


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From: ghudson@mit.edu (Greg Hudson)
Newsgroups: comp.os.linux.misc,comp.os.linux.development.system,comp.os.linux.networking,comp.unix.bsd.bsdi.misc,comp.unix.bsd.netbsd.misc,comp.unix.bsd.freebsd.misc
Subject: Re: need secure OS to entrust millions to
Followup-To: comp.os.linux.misc,comp.os.linux.development.system,comp.os.linux.networking,comp.unix.bsd.bsdi.misc,comp.unix.bsd.netbsd.misc,comp.unix.bsd.freebsd.misc
Date: 11 Mar 1996 04:54:03 GMT
Organization: Massachvsetts Institvte of Technology
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Terry Lambert (terry@lambert.org) wrote:
: Your definition is predicated on the obscurity of a fast-factoring
: algorithm.

: Is it your claim that such an algorithm is impossible?

No.  Factoring is a problem theorized to be hard, but there's not
currently any proof of this.

Of course, there's nothing special about factoring as a mathematical
problem, except that it's been heavily analyzed by the academic
community.  Coming up with an IDEA secret key given a known
plaintext is also a mathematical problem, which hasn't been analyzed
nearly as much.

: I refer you to Godel's Theorem.

You're confused.  If you think you're not confused, please explain
the relevance of Godel's First (or Second) Incompleteness Theorem
to this problem.  You may assume that I'm familiar with the theorem.

: Typical "security through obscurity" is hiding a key in a
: search space, but not securing the location of the key itself.

If you honestly believe that that is the common definition, then
I'd appreciate it if you'd provide a reference.  Certainly, it is
not what the poster I responded to was referring to by "security
"security through obscurity."

: You see, I believe the NSA already has fast-factoring
: capability based on the questions Robert Morris Senior (formerly
: of the NSA) posed at a recent security conference.

I'm happy that you know how to speculate.  I can speculate that the
NSA has a way to break any cryptosystem you come up with except
one-time pads.

: All that's required to crack RSA is massive parallelism and a
: willingness to epend the effort, and that's assuming nothing
: more than a brute-force attack.

If, as the key size increases, the effort required to break a
cryptosystem expands sufficiently faster than the effort required
to use the cryptosystem legitimately, then there will always be a
key size which will defeat an arbitrarily amount of parallelism
and time.  Back-of-the-envelope calculations suggest that a
1024-bit product of two primes would require absurd amounts of
time to factor even if every particle in the known universe were
a supercomputer.  Of course, if you speculate that the NSA has
arbitrarily good factoring algorithms, you will never find a
satisfactory key size.