[IP] The second sincerest form of flattery (fwd from dave@farber.net)

2005-01-20 Thread Eugen Leitl
- Forwarded message from David Farber [EMAIL PROTECTED] -

From: David Farber [EMAIL PROTECTED]
Date: Thu, 20 Jan 2005 06:02:23 -0500
To: Ip ip@v2.listbox.com
Subject: [IP] The second sincerest form of flattery
User-Agent: Microsoft-Entourage/11.1.0.040913
Reply-To: [EMAIL PROTECTED]


-- Forwarded Message
From: Matt Blaze [EMAIL PROTECTED]
Date: Wed, 19 Jan 2005 20:53:58 -0500
To: David Farber [EMAIL PROTECTED]
Subject: The second sincerest form of flattery

One of my research interests is applying the principles of
human-scale security (such as mechanical locks and alarm systems) to
computer science.  Although human-scale systems are almost always
imperfect, their failure mechanisms are often much more gradual and
more predictable than their information systems counterparts, and I
believe that by better understanding why this is we might be able to
build computer systems that behave in similar ways.

Several particularly interesting illustrations of the phenomenon of
gradual and predictable security failure can be found in safes and
vaults.  I'm working on a survey paper, tentatively entitled
Safecracking for the computer scientist, that I hope will stimulate
other researchers to think along similar lines.  Last month I finished
a first draft and put it on my web site.  (For those who've not seen
it, it's at http://www.crypto.com/papers/safelocks.pdf )

Although the paper is only of rather narrow interest, a couple of
weeks ago the wildly popular Slashdot news site discovered and
linked to the draft; somewhere around 50,000 people downloaded the
(large) pdf file that weekend.

My web server survived Slashdot's attention, but I was somewhat taken
aback by what happened next.

A couple of years ago I wrote a paper about weaknesses in the
keyspaces of master-keyed mechanical locks (it marked the beginning of
my understanding of the similarities between information and physical
security).  Some locksmiths were outraged that I would publish a paper
revealing security vulnerabilities in what they believed to be a
closed field.  See http://www.crypto.com/papers/kiss.html for details,
but to make a long story short, some locksmiths do not approve of
disclosing vulnerabilities in locks to the general public, on the
grounds that open discussion aids the bad guys more than it helps the
good guys.  (I don't agree -- and the scientific method's requirement
for open scrutiny and debate does not provide an exemption when the
subject involves security -- but that's another story for another
time.)

Perhaps predictably, there has been a similar reaction to my recent
draft on safe locks.  Shortly after Slashdot linked to the paper, one
or more locksmithing trade groups discovered it as well .  The
response of some locksmiths to the draft has been at least as negative
as it was to my master keying paper.  I've received quite a bit of
uncomplimentary email from locksmiths, and I'm told that locksmithing
message boards have recently been abuzz with messages about what a
scoundrel I must be to again have written such an unethical and
irresponsible paper.

Ironically, the theme of my safecracking survey is that while safes
aren't perfect, they largely meet their requirements, and indeed,
computer security would do well to emulate their security principles.
Nothing in my paper (and indeed, no techniques of which I'm aware)
allow one to quickly open decent quality safes.  The paper's
conclusion is that even if one is fluent in the (not very) secrets of
the safecracking trade, the measurable security of even relatively
modest safes allows them to be used quite effectively for their
intended applications (especially as part of larger security system
that complement the safes' limitations).  I certainly don't think it
would have been unethical to have published an analysis that reached a
different conclusion, of course, but my paper as written could hardly
be considered an attack against the safe industry or its products.

As with the reaction to my master keying paper, many of the complaints
I've received are self-contradictory and emotionally charged, often
invoking homeland security in unspecified but ominous ways.  I've
developed a thick skin against this sort of thing, and I try not to
take it personally (although it's a bit disturbing to have so many
people so angry with me over my work).  It's rather like being accused
of witchcraft; many of the complainers don't seem to be seeking a
reasoned debate but are instead venting a broder range of unspoken
frustrations that go well beyond either me or my papers.  There is
simply no effective way to debate on these terms against an angry mob.

In any case, some locksmiths are apparently trying to organize a
letter writing campaign aimed at various officials at my university,
and I'm told that my department chair, my dean, the provost, and the
head of campus security have each received (a handful of) letters
complaining about me.  While Penn's support for the basic 

Scientific American on Quantum Encryption

2005-01-20 Thread Eugen Leitl

Scientific American has little clue, as usual (see their nanotechnology
retraction).

Link: http://slashdot.org/article.pl?sid=05/01/20/0358215
Posted by: samzenpus, on 2005-01-20 06:35:00

   from the just-try-and-break-it dept.
   [1]prostoalex writes Scientific American claims that [2]advances in
   commercially available quantum encryption might obsolete the existing
   factorization-based solutions: The National Security Agency or one of
   the Federal Reserve banks can now buy a quantum-cryptographic system
   from two small companies - and more products are on the way. This new
   method of encryption represents the first major commercial
   implementation for what has become known as quantum information
   science, which blends quantum mechanics and information theory. The
   ultimate technology to emerge from the field may be a quantum computer
   so powerful that the only way to protect against its prodigious
   code-breaking capability may be to deploy quantum-cryptographic
   techniques.

   IFRAME: [3]pos6

References

   1. http://www.everythingfirebird.com/
   2. 
http://www.sciam.com/article.cfm?chanID=sa006articleID=000479CD-F58C-11BE-AD0683414B7Fref=rdf

- End forwarded message -

December 20, 2004

Best-Kept Secrets

Quantum cryptography has marched from theory to laboratory to real products

By Gary Stix

At the IBM Thomas J. Watson Research Laboratory, Charles Bennett is known as
a brilliant theoretician--one of the fathers of the emerging field of quantum
computing. Like many theorists, he has not logged much experience in the
laboratory. His absentmindedness in relation to the physical world once
transformed the color of a teapot from green to red when he left it on a
double boiler too long. But in 1989 Bennett and colleagues John A. Smolin and
Gilles Brassard cast caution aside and undertook a groundbreaking experiment
that would demonstrate a new cryptography based on the principles of quantum
mechanics.

The team put together an experiment in which photons moved down a
30-centimeter channel in a light-tight box called Aunt Martha's coffin. The
direction in which the photons oscillated, their polarization, represented
the 0s or 1s of a series of quantum bits, or qubits. The qubits constituted a
cryptographic key that could be used to encrypt or decipher a message. What
kept the key from prying eavesdroppers was Heisenberg's uncertainty
principle--a foundation of quantum physics that dictates that the measurement
of one property in a quantum state will perturb another. In a quantum
cryptographic system, any interloper tapping into the stream of photons will
alter them in a way that is detectable to the sender and the receiver. In
principle, the technique provides the makings of an unbreakable cryptographic
key.

Today quantum cryptography has come a long way from the jury-rigged project
assembled on a table in Bennett's office. The National Security Agency or one
of the Federal Reserve banks can now buy a quantum-cryptographic system from
two small companies--and more products are on the way. This new method of
encryption represents the first major commercial implementation for what has
become known as quantum information science, which blends quantum mechanics
and information theory. The ultimate technology to emerge from the field may
be a quantum computer so powerful that the only way to protect against its
prodigious code-breaking capability may be to deploy quantum-cryptographic
techniques.

The arrival of the quantum computer may portend the eventual demise of
ciphers based on factorization.

The challenge modern cryptographers face is for sender and receiver to share
a key while ensuring that no one has filched a copy. A method called
public-key cryptography is often used to distribute the secret keys for
encryption and decoding of a full-length message. The security of public-key
cryptography depends on factorization or other difficult mathematical
problems. It is easy to compute the product of two large numbers but
extremely hard to factor it back into the primes. The popular RSA cipher
algorithm, widely deployed in public-key cryptography, relies on
factorization. The secret key being transferred between sender and receiver
is encrypted with a publicly available key, say, a large number such as
408,508,091 (in practice, the number would be much larger). It can be
decrypted only with a private key owned by the recipient of the data, made up
of two factors, in this case 18,313 and 22,307.

The difficulty of overcoming a public-key cipher may hold secret keys secure
for a decade or more. But the advent of the quantum information era--and, in
particular, the capability of quantum computers to rapidly perform
monstrously challenging factorizations--may portend the eventual demise of
RSA and other cryptographic schemes. If quantum computers become a reality,
the whole game changes, says John Rarity, a 

Re: Scientific American on Quantum Encryption

2005-01-20 Thread Justin
On 2005-01-20T12:16:34+0100, Eugen Leitl wrote:
 Scientific American has little clue, as usual (see their nanotechnology
 retraction).

How could they possibly get clue?  Scientists don't want to write
pop-sci articles for a living.  It's impossible to condense most current
research down to digestible kernels that the masses can understand.
SciAm should close down, requiring those who care about science to learn
enough about it to read science journals.

Professors who can teach a QM course well in a semester are rare enough.
I doubt any one of them could write a 5000 word article on quantum
entanglement that would be intelligible to the average cretinous
American who wants to seem smart by reading Sci-Am.  If they want to be
smart, they can start by picking up an undergrad-level book on QM.  But
that requires much effort to read, unlike a glossy 5000 word article.

Journalism should not be a college major.  Journalists in the main know
little about how to write and interview, and less about the topics they
write on.  They don't understand that being able to write (and in many
cases even that ability is in serious doubt) doesn't qualify them to
write on any topic they choose.  Many journalists aren't qualified to
write on anything, not even journalism.

-- 
War is the father and king of all, and some he shows as gods, others as
men; some he makes slaves, others free.  --Heraclitus (Kahn.83/D-K.53)



RE: Scientific American on Quantum Encryption

2005-01-20 Thread Trei, Peter
I've actually seen these devices in operation. The thing
that impressed me most was that the path need not be a
single fiber from end to end - you can maintain quantum 
state across a switchable fiber junction. This means 
you are no longer limited to a single pair of boxes talking to 
each other.

True, the SciAm article doesn't address a lot of issues,
but the fact remains that this technology is interesting
and important.

Peter Trei

 -Original Message-
 From: [EMAIL PROTECTED]
 [mailto:[EMAIL PROTECTED] Behalf Of Eugen Leitl
 Sent: Thursday, January 20, 2005 6:17 AM
 To: [EMAIL PROTECTED]
 Cc: [EMAIL PROTECTED]
 Subject: Scientific American on Quantum Encryption
 
 
 
 Scientific American has little clue, as usual (see their 
 nanotechnology
 retraction).
 
 Link: http://slashdot.org/article.pl?sid=05/01/20/0358215
 Posted by: samzenpus, on 2005-01-20 06:35:00
 
from the just-try-and-break-it dept.
[1]prostoalex writes Scientific American claims that 
 [2]advances in
commercially available quantum encryption might obsolete 
 the existing
factorization-based solutions: The National Security 
 Agency or one of
the Federal Reserve banks can now buy a 
 quantum-cryptographic system
from two small companies - and more products are on the 
 way. This new
method of encryption represents the first major commercial
implementation for what has become known as quantum information
science, which blends quantum mechanics and information theory. The
ultimate technology to emerge from the field may be a 
 quantum computer
so powerful that the only way to protect against its prodigious
code-breaking capability may be to deploy quantum-cryptographic
techniques.

 




Re: Scientific American on Quantum Encryption

2005-01-20 Thread Eugen Leitl
On Thu, Jan 20, 2005 at 10:47:38AM -0500, Trei, Peter wrote:

 I've actually seen these devices in operation. The thing
 that impressed me most was that the path need not be a
 single fiber from end to end - you can maintain quantum 
 state across a switchable fiber junction. This means 

Very impressive. If they manage to keep the entanglement all the way up to
LEO by line of sight it would be even more impressive 
(anyone thinks this can be done at all?)

 you are no longer limited to a single pair of boxes talking to 
 each other.

What makes it very important is early beginnings of practical quantum
computing. Will photonics and spintronics in solid state at RT play well with
each other? Will error correction scale to large qubit register sizes? Will
the algorithm space be large and rich enough to be practical? All very
interesting questions Scientific American fails to raise.
 
 True, the SciAm article doesn't address a lot of issues,
 but the fact remains that this technology is interesting
 and important.

I agree that this technology is interesting and important, but not for what
it claims to be used for. Quantum encryption right now is a tool to milk the
gullible, and hence very much crypto snake oil.

For these distances one-time pads by trusted couriers would seem so much more
practical and so much cheaper.

-- 
Eugen* Leitl a href=http://leitl.org;leitl/a
__
ICBM: 48.07078, 11.61144http://www.leitl.org
8B29F6BE: 099D 78BA 2FD3 B014 B08A  7779 75B0 2443 8B29 F6BE
http://moleculardevices.org http://nanomachines.net


pgp16rmpRSXZx.pgp
Description: PGP signature


RE: Scientific American on Quantum Encryption

2005-01-20 Thread Trei, Peter
Eugen Leitl wrote:

 On Thu, Jan 20, 2005 at 10:47:38AM -0500, Trei, Peter wrote:
 
  I've actually seen these devices in operation. The thing
  that impressed me most was that the path need not be a
  single fiber from end to end - you can maintain quantum 
  state across a switchable fiber junction. This means 
 
 Very impressive. If they manage to keep the entanglement all 
 the way up to
 LEO by line of sight it would be even more impressive 
 (anyone thinks this can be done at all?)
 
  you are no longer limited to a single pair of boxes talking to 
  each other.

At the moment, the practical limit in fiber is around 150 km

Getting to LEO is a *lot* harder - remember, you're throwing
and catching one photon at a time - a beam that spreads wider than
your detector is usually going to miss the detector.

Peter Trei




Re: Scientific American on Quantum Encryption

2005-01-20 Thread Tyler Durden
Well, I think you've been a little too harsh on Scientific American. In the 
past a lot of the best articles were written by the pioneers in their 
fields. In fact, it's where I believe Wittfield and Diffie wrote a great 
piece on their work.

And don't expect anyone (not even a math major) to go grab a quantum 
mechanics textbook and be able to get anything out of it. One would really 
need to have done the classical coursework in order to understand it (or at 
least to know enough to be spurised by it). And if you don't have the math 
then forget about it. Meanwhile, it IS possible to write intelligently on 
quantum entanglement, EPR and Aharnov-Bohm, and it's been done by Sci-Am, 
Penrose, Kaku and plenty of others.

-TD
From: Justin [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Subject: Re: Scientific American on Quantum Encryption
Date: Thu, 20 Jan 2005 15:23:35 +
On 2005-01-20T12:16:34+0100, Eugen Leitl wrote:
 Scientific American has little clue, as usual (see their nanotechnology
 retraction).
How could they possibly get clue?  Scientists don't want to write
pop-sci articles for a living.  It's impossible to condense most current
research down to digestible kernels that the masses can understand.
SciAm should close down, requiring those who care about science to learn
enough about it to read science journals.
Professors who can teach a QM course well in a semester are rare enough.
I doubt any one of them could write a 5000 word article on quantum
entanglement that would be intelligible to the average cretinous
American who wants to seem smart by reading Sci-Am.  If they want to be
smart, they can start by picking up an undergrad-level book on QM.  But
that requires much effort to read, unlike a glossy 5000 word article.
Journalism should not be a college major.  Journalists in the main know
little about how to write and interview, and less about the topics they
write on.  They don't understand that being able to write (and in many
cases even that ability is in serious doubt) doesn't qualify them to
write on any topic they choose.  Many journalists aren't qualified to
write on anything, not even journalism.
--
War is the father and king of all, and some he shows as gods, others as
men; some he makes slaves, others free.  --Heraclitus (Kahn.83/D-K.53)



RE: Scientific American on Quantum Encryption

2005-01-20 Thread Tyler Durden
What do you mean? By a physical fiber switch? That's certainly possible, 
though you'd need a very good condition switch to be able to do it. I'd bet 
if that switch switched a lot, the QCrypto channel would eventually be 
unusable.

If you're talking about a WDM element or passive splitter or other purely 
optical component, then you'd need some kind of error correction (in the 
digital domain) in order to overcome the fact that many of the photons will 
not choose to go in the direction you want.

In the long run I think we'll see some small proliferation, but given the 
level of integration and how well current coding schemes work, I'd guess 
this will remain a niche unless there's a major breakthrough in factoring.

-TD

From: Trei, Peter [EMAIL PROTECTED]
To: Eugen Leitl [EMAIL PROTECTED], [EMAIL PROTECTED]
CC: [EMAIL PROTECTED]
Subject: RE: Scientific American on Quantum Encryption
Date: Thu, 20 Jan 2005 10:47:38 -0500
I've actually seen these devices in operation. The thing
that impressed me most was that the path need not be a
single fiber from end to end - you can maintain quantum
state across a switchable fiber junction. This means
you are no longer limited to a single pair of boxes talking to
each other.
True, the SciAm article doesn't address a lot of issues,
but the fact remains that this technology is interesting
and important.
Peter Trei
 -Original Message-
 From: [EMAIL PROTECTED]
 [mailto:[EMAIL PROTECTED] Behalf Of Eugen Leitl
 Sent: Thursday, January 20, 2005 6:17 AM
 To: [EMAIL PROTECTED]
 Cc: [EMAIL PROTECTED]
 Subject: Scientific American on Quantum Encryption



 Scientific American has little clue, as usual (see their
 nanotechnology
 retraction).

 Link: http://slashdot.org/article.pl?sid=05/01/20/0358215
 Posted by: samzenpus, on 2005-01-20 06:35:00

from the just-try-and-break-it dept.
[1]prostoalex writes Scientific American claims that
 [2]advances in
commercially available quantum encryption might obsolete
 the existing
factorization-based solutions: The National Security
 Agency or one of
the Federal Reserve banks can now buy a
 quantum-cryptographic system
from two small companies - and more products are on the
 way. This new
method of encryption represents the first major commercial
implementation for what has become known as quantum information
science, which blends quantum mechanics and information theory. The
ultimate technology to emerge from the field may be a
 quantum computer
so powerful that the only way to protect against its prodigious
code-breaking capability may be to deploy quantum-cryptographic
techniques.



Amazon Gift Certificate/MPAK IP-SAN Solutions

2005-01-20 Thread MPAK Technologies, Inc.
Title: IP-SAN Suites-Amazon Promotion





  
 
  
  
  
  
  
  
  
  

 
  
  

 
  
  
  
  

 
  
  

 
  
  
  
  

 
  
  

 
  
   

   






  
   



  

  
  
  

 
  
  

  


  


  
  


  
  
  
  
  







RE: Scientific American on Quantum Encryption

2005-01-20 Thread Trei, Peter
I've actually seen these devices in operation. The thing
that impressed me most was that the path need not be a
single fiber from end to end - you can maintain quantum 
state across a switchable fiber junction. This means 
you are no longer limited to a single pair of boxes talking to 
each other.

True, the SciAm article doesn't address a lot of issues,
but the fact remains that this technology is interesting
and important.

Peter Trei

 -Original Message-
 From: [EMAIL PROTECTED]
 [mailto:[EMAIL PROTECTED] Behalf Of Eugen Leitl
 Sent: Thursday, January 20, 2005 6:17 AM
 To: [EMAIL PROTECTED]
 Cc: [EMAIL PROTECTED]
 Subject: Scientific American on Quantum Encryption
 
 
 
 Scientific American has little clue, as usual (see their 
 nanotechnology
 retraction).
 
 Link: http://slashdot.org/article.pl?sid=05/01/20/0358215
 Posted by: samzenpus, on 2005-01-20 06:35:00
 
from the just-try-and-break-it dept.
[1]prostoalex writes Scientific American claims that 
 [2]advances in
commercially available quantum encryption might obsolete 
 the existing
factorization-based solutions: The National Security 
 Agency or one of
the Federal Reserve banks can now buy a 
 quantum-cryptographic system
from two small companies - and more products are on the 
 way. This new
method of encryption represents the first major commercial
implementation for what has become known as quantum information
science, which blends quantum mechanics and information theory. The
ultimate technology to emerge from the field may be a 
 quantum computer
so powerful that the only way to protect against its prodigious
code-breaking capability may be to deploy quantum-cryptographic
techniques.

 




OpenVPN

2005-01-20 Thread Eugen Leitl

If you haven't checked it out yet, you should. Really easy to set up (two 
Windows
XP machines through a NAT on DSL, ping ~50 ms, preshared key, single port open; 
right now). 
Looking forward to see how C3-accelerated AES (OpenSSL next stable will support 
it out of the box) will do, across multiple platforms.

Le IPsec c'est mort, vive le OpenVPN.

-- 
Eugen* Leitl a href=http://leitl.org;leitl/a
__
ICBM: 48.07078, 11.61144http://www.leitl.org
8B29F6BE: 099D 78BA 2FD3 B014 B08A  7779 75B0 2443 8B29 F6BE
http://moleculardevices.org http://nanomachines.net


pgpj4YzslDNi2.pgp
Description: PGP signature


Re: Scientific American on Quantum Encryption

2005-01-20 Thread Justin
On 2005-01-20T12:16:34+0100, Eugen Leitl wrote:
 Scientific American has little clue, as usual (see their nanotechnology
 retraction).

How could they possibly get clue?  Scientists don't want to write
pop-sci articles for a living.  It's impossible to condense most current
research down to digestible kernels that the masses can understand.
SciAm should close down, requiring those who care about science to learn
enough about it to read science journals.

Professors who can teach a QM course well in a semester are rare enough.
I doubt any one of them could write a 5000 word article on quantum
entanglement that would be intelligible to the average cretinous
American who wants to seem smart by reading Sci-Am.  If they want to be
smart, they can start by picking up an undergrad-level book on QM.  But
that requires much effort to read, unlike a glossy 5000 word article.

Journalism should not be a college major.  Journalists in the main know
little about how to write and interview, and less about the topics they
write on.  They don't understand that being able to write (and in many
cases even that ability is in serious doubt) doesn't qualify them to
write on any topic they choose.  Many journalists aren't qualified to
write on anything, not even journalism.

-- 
War is the father and king of all, and some he shows as gods, others as
men; some he makes slaves, others free.  --Heraclitus (Kahn.83/D-K.53)



Re: Scientific American on Quantum Encryption

2005-01-20 Thread Eugen Leitl
On Thu, Jan 20, 2005 at 10:47:38AM -0500, Trei, Peter wrote:

 I've actually seen these devices in operation. The thing
 that impressed me most was that the path need not be a
 single fiber from end to end - you can maintain quantum 
 state across a switchable fiber junction. This means 

Very impressive. If they manage to keep the entanglement all the way up to
LEO by line of sight it would be even more impressive 
(anyone thinks this can be done at all?)

 you are no longer limited to a single pair of boxes talking to 
 each other.

What makes it very important is early beginnings of practical quantum
computing. Will photonics and spintronics in solid state at RT play well with
each other? Will error correction scale to large qubit register sizes? Will
the algorithm space be large and rich enough to be practical? All very
interesting questions Scientific American fails to raise.
 
 True, the SciAm article doesn't address a lot of issues,
 but the fact remains that this technology is interesting
 and important.

I agree that this technology is interesting and important, but not for what
it claims to be used for. Quantum encryption right now is a tool to milk the
gullible, and hence very much crypto snake oil.

For these distances one-time pads by trusted couriers would seem so much more
practical and so much cheaper.

-- 
Eugen* Leitl a href=http://leitl.org;leitl/a
__
ICBM: 48.07078, 11.61144http://www.leitl.org
8B29F6BE: 099D 78BA 2FD3 B014 B08A  7779 75B0 2443 8B29 F6BE
http://moleculardevices.org http://nanomachines.net


pgpIzevOdZDJw.pgp
Description: PGP signature


Re: OpenVPN

2005-01-20 Thread Alexandre Dulaunoy
On Wed, 19 Jan 2005, Eugen Leitl wrote:

 
 If you haven't checked it out yet, you should. Really easy to set up (two 
 Windows
 XP machines through a NAT on DSL, ping ~50 ms, preshared key, single port 
 open; right now). 
 Looking forward to see how C3-accelerated AES (OpenSSL next stable will 
 support 
 it out of the box) will do, across multiple platforms.
 
 Le IPsec c'est mort, vive le OpenVPN.

On peut le dire ;-)

The author of  OpenVPN is very open to discussion  for fixing bugs and
adding new  functionalities. OpenVPN is  also working quite  well over
satellite and high-latency links... 

-- 
--   Alexandre Dulaunoy (adulau) -- http://www.foo.be/
-- http://pgp.ael.be:11371/pks/lookup?op=getsearch=0x44E6CBCD
-- Knowledge can create problems, it is not through ignorance
--that we can solve them Isaac Asimov



RE: Scientific American on Quantum Encryption

2005-01-20 Thread Trei, Peter
Eugen Leitl wrote:

 On Thu, Jan 20, 2005 at 10:47:38AM -0500, Trei, Peter wrote:
 
  I've actually seen these devices in operation. The thing
  that impressed me most was that the path need not be a
  single fiber from end to end - you can maintain quantum 
  state across a switchable fiber junction. This means 
 
 Very impressive. If they manage to keep the entanglement all 
 the way up to
 LEO by line of sight it would be even more impressive 
 (anyone thinks this can be done at all?)
 
  you are no longer limited to a single pair of boxes talking to 
  each other.

At the moment, the practical limit in fiber is around 150 km

Getting to LEO is a *lot* harder - remember, you're throwing
and catching one photon at a time - a beam that spreads wider than
your detector is usually going to miss the detector.

Peter Trei




Re: Scientific American on Quantum Encryption

2005-01-20 Thread Tyler Durden
Well, I think you've been a little too harsh on Scientific American. In the 
past a lot of the best articles were written by the pioneers in their 
fields. In fact, it's where I believe Wittfield and Diffie wrote a great 
piece on their work.

And don't expect anyone (not even a math major) to go grab a quantum 
mechanics textbook and be able to get anything out of it. One would really 
need to have done the classical coursework in order to understand it (or at 
least to know enough to be spurised by it). And if you don't have the math 
then forget about it. Meanwhile, it IS possible to write intelligently on 
quantum entanglement, EPR and Aharnov-Bohm, and it's been done by Sci-Am, 
Penrose, Kaku and plenty of others.

-TD
From: Justin [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Subject: Re: Scientific American on Quantum Encryption
Date: Thu, 20 Jan 2005 15:23:35 +
On 2005-01-20T12:16:34+0100, Eugen Leitl wrote:
 Scientific American has little clue, as usual (see their nanotechnology
 retraction).
How could they possibly get clue?  Scientists don't want to write
pop-sci articles for a living.  It's impossible to condense most current
research down to digestible kernels that the masses can understand.
SciAm should close down, requiring those who care about science to learn
enough about it to read science journals.
Professors who can teach a QM course well in a semester are rare enough.
I doubt any one of them could write a 5000 word article on quantum
entanglement that would be intelligible to the average cretinous
American who wants to seem smart by reading Sci-Am.  If they want to be
smart, they can start by picking up an undergrad-level book on QM.  But
that requires much effort to read, unlike a glossy 5000 word article.
Journalism should not be a college major.  Journalists in the main know
little about how to write and interview, and less about the topics they
write on.  They don't understand that being able to write (and in many
cases even that ability is in serious doubt) doesn't qualify them to
write on any topic they choose.  Many journalists aren't qualified to
write on anything, not even journalism.
--
War is the father and king of all, and some he shows as gods, others as
men; some he makes slaves, others free.  --Heraclitus (Kahn.83/D-K.53)



RE: Scientific American on Quantum Encryption

2005-01-20 Thread Tyler Durden
What do you mean? By a physical fiber switch? That's certainly possible, 
though you'd need a very good condition switch to be able to do it. I'd bet 
if that switch switched a lot, the QCrypto channel would eventually be 
unusable.

If you're talking about a WDM element or passive splitter or other purely 
optical component, then you'd need some kind of error correction (in the 
digital domain) in order to overcome the fact that many of the photons will 
not choose to go in the direction you want.

In the long run I think we'll see some small proliferation, but given the 
level of integration and how well current coding schemes work, I'd guess 
this will remain a niche unless there's a major breakthrough in factoring.

-TD

From: Trei, Peter [EMAIL PROTECTED]
To: Eugen Leitl [EMAIL PROTECTED], [EMAIL PROTECTED]
CC: [EMAIL PROTECTED]
Subject: RE: Scientific American on Quantum Encryption
Date: Thu, 20 Jan 2005 10:47:38 -0500
I've actually seen these devices in operation. The thing
that impressed me most was that the path need not be a
single fiber from end to end - you can maintain quantum
state across a switchable fiber junction. This means
you are no longer limited to a single pair of boxes talking to
each other.
True, the SciAm article doesn't address a lot of issues,
but the fact remains that this technology is interesting
and important.
Peter Trei
 -Original Message-
 From: [EMAIL PROTECTED]
 [mailto:[EMAIL PROTECTED] Behalf Of Eugen Leitl
 Sent: Thursday, January 20, 2005 6:17 AM
 To: [EMAIL PROTECTED]
 Cc: [EMAIL PROTECTED]
 Subject: Scientific American on Quantum Encryption



 Scientific American has little clue, as usual (see their
 nanotechnology
 retraction).

 Link: http://slashdot.org/article.pl?sid=05/01/20/0358215
 Posted by: samzenpus, on 2005-01-20 06:35:00

from the just-try-and-break-it dept.
[1]prostoalex writes Scientific American claims that
 [2]advances in
commercially available quantum encryption might obsolete
 the existing
factorization-based solutions: The National Security
 Agency or one of
the Federal Reserve banks can now buy a
 quantum-cryptographic system
from two small companies - and more products are on the
 way. This new
method of encryption represents the first major commercial
implementation for what has become known as quantum information
science, which blends quantum mechanics and information theory. The
ultimate technology to emerge from the field may be a
 quantum computer
so powerful that the only way to protect against its prodigious
code-breaking capability may be to deploy quantum-cryptographic
techniques.