[extropy-chat] Encryption revolution

Tue Dec 9 16:11:35 UTC 2003

>From: Eugen Leitl <eugen at leitl.org>
>To: ExI chat list <extropy-chat at lists.extropy.org>
>Subject: Re: [extropy-chat] Encryption revolution
>Date: Tue, 9 Dec 2003 15:33:27 +0100

>Please refrain from using blanket statements about a domain you obviously
>don't understand. "pretty strong" is meaningless without an attack model,
>"easy to use" is ridiculous, unless you refer to peer-reviewed
>implementations of PKIs, which have an empiric record track of being
>insecure. People who thought PKI was easy to write kept producing buggy
>shitware. Because they thought it "easy to use".

Please refrain from using blanket statements about a domain you obviously 
don't understand.

"Pretty strong" is not meaningless. As a cryptography consumer, I won't 
write the software myself but I need to know that it is difficult or 
pratically impossible to compromise.

>The key size is useless without knowing the algorithm complexity. No, it is 
>not possible
>to brute-force a symmetric crypto key within its viability window.

The key size is not useless. Of course to make a perfect valuation you need 
to know what algorithm is used.

>All PKI systems are used for symmetric encryption key exchange. In fact, 
>most
>PKI has considerable weaknesses, if it's being used for something else than
>that.
See, here's another of your blanket statements. Not All PKI systems are used 
for symmetric encryption. There are plenty of insecure systems that use PKI 
for things they shouldn't use them for.

>Please do not assume reading Slashdot is sufficient to understand
>cryptography (No, reading cryptography@ over years is not sufficient,
>either, or just reading <http://www.cacr.math.uwaterloo.ca/hac/> ,
>but it's a first start if you want to understand the basics
>of cryptography).
Everyone knows that true cypherpunks learn from reading Cryptonomicon, not 
slashdot. Man, I thought you would have known that.

I'm not trying to get into a pissing match with you, just trying to ablate 
your abrasiveness a little.

BAL

>From: Eugen Leitl <eugen at leitl.org>
>Reply-To: ExI chat list <extropy-chat at lists.extropy.org>
>To: ExI chat list <extropy-chat at lists.extropy.org>
>Subject: Re: [extropy-chat] Encryption revolution
>Date: Tue, 9 Dec 2003 15:33:27 +0100
>
>On Sun, Dec 07, 2003 at 09:15:14PM -0500, Brian Alexander Lee wrote:
> > I think you're right. The real reason there's so much funding for 
>quantum
> > encryption is because whomever gets it first will have "unbreakable"
>
>Do you trust the laws of physics (these you know, that is, and you do know
>that we know our current physics is inconsistent, and hence knowably
>incomplete?) or those of mathematics?
>
>Cryptoanalysis is a mature, understood discipline. There are several
>independant-fields-of-theory production-quality PKI systems.
>
>Not many people understand QM, even less people understand the limitations
>of hardware using QM (single-photon source? proof of entanglement? 
>detection
>of cloning?).
>
>http://www.interhack.net/people/cmcurtin/snake-oil-faq.html
>
> > encryption for a while. It's like nuclear weapons were, you don't want 
>to be
> > the one without it.
>
>The only provably secure cryptosystem is one-time pad, generated
>using a good source of entropy and properly whitened. The second best one
>is a good (hairy territory, this) PRNG seeded by a shared secret. PKI
>is where you're stuck with no shared secret, and only open channels.
>
> > Public key encryption is pretty strong and easy to use, but it has a few
>
>Please refrain from using blanket statements about a domain you obviously
>don't understand. "pretty strong" is meaningless without an attack model,
>"easy to use" is ridiculous, unless you refer to peer-reviewed
>implementations of PKIs, which have an empiric record track of being
>insecure. People who thought PKI was easy to write kept producing buggy
>shitware. Because they thought it "easy to use".
>
>They're not the weak link in majority of cases, agreed.
>
> > flaws that theoretically a really big gov't computer could use to break 
>it.
> > A lot of encryption systems that use public key really use it to 
>generate a
> > 120-160bit session key and exchange it with their partner. Although 
>there
>
>All PKI systems are used for symmetric encryption key exchange. In fact, 
>most
>PKI has considerable weaknesses, if it's being used for something else than
>that.
>
> > are no documented cracks of 120 bit encryption through brute force, it's
> > theoretically possible.
>
>The key size is useless without knowing the algorithm complexity. No, it is 
>not possible
>to brute-force a symmetric crypto key within its viability window. It is
>perfectly possible (though impractical) to use key sizes which cannot
>be brute-forced, period. This includes QC, because not all algorithms
>can profit from QC parallelism; nevermind that you can't scale to
>high qubit numbers (barring error-correction, the problem is energy
>efficiency being worse than classical computation).
>
> > Harvey pointed out a lot of common vulnerabilities, but most of them can 
>be
> > avoided by using proper techniques to avoid timing, social engineering, 
>etc.
> >
> > The big benefit of this is that it allows for a secure key transmission
> > technique. Proper use of certificates should prevent a man in the middle
> > exploit.
>
>You cannot detect a MITM with PKI alone. The QM is there as an (imperfect)
>tampering detection.
>
> > Nonetheless, crypttech is growing by leaps and bounds as corporations 
>now
> > need encryption where previously just terrorists and govt's needed it.
>
>Please do not assume reading Slashdot is sufficient to understand
>cryptography (No, reading cryptography@ over years is not sufficient,
>either, or just reading <http://www.cacr.math.uwaterloo.ca/hac/> ,
>but it's a first start if you want to understand the basics
>of cryptography).
>
>-- Eugen* Leitl <a href="http://leitl.org">leitl</a>
>______________________________________________________________
>ICBM: 48.07078, 11.61144            http://www.leitl.org
>8B29F6BE: 099D 78BA 2FD3 B014 B08A  7779 75B0 2443 8B29 F6BE
>http://moleculardevices.org         http://nanomachines.net
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