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Key distribution via nonlocal quantum effects

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John Nagle

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Jun 28, 1992, 11:23:31 PM6/28/92
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Scientific American (July 1992, page 100) notes briefly that
Charles Bennett at IBM's Watson Research Center has built a device for
transmitting a random number safely using the Einstein-Podolsky-Rosen
effect. This is a concept so wierd that I won't even try to describe it.
I suggest reading the article. But it suggests that the untappable
distribution of keys, protected by the "observer effect" in quantum
mechanics, may be possible.

John Nagle

Colin Plumb

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Jun 29, 1992, 8:49:58 PM6/29/92
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Gilles Brassard in Montreal has been working on this for a while, and
has a working prototype. Secure against infinite computational power.
As I put it, The Lorg God Himself, given access only to the channel,
couldn't do better than block communications.

Actually, the quantum channel just provices mostly-shared mostly-secret
bits. An interloper cannot monitor undetectably, so the communicators
can resolve errors between them, then use the number of detected errors
to compute an upper bound on the eavesdropper's knowledge and throw
away some of the bits to get a shorter, but secure (eavesdropoer's
knowledge limited by 2^-n bits, where n is the number of bits above the
minimum required that are thrown away) shared random bit string.

Then you can use this for one-time pads, secure authentication, etc.

Neat stuff.
--
-Colin

Harry Carter

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Jul 2, 1992, 12:15:08 AM7/2/92
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(Ellipses are mine. - Harry)

co...@eecg.toronto.edu (Colin Plumb) writes:

>In article <#dxlh8...@netcom.com> na...@netcom.com (John Nagle) writes:
>> Scientific American (July 1992, page 100) notes briefly that
>>Charles Bennett at IBM's Watson Research Center has built a device for
>>transmitting a random number safely using the Einstein-Podolsky-Rosen
>>effect. This is a concept so wierd that I won't even try to describe it.

>>I suggest reading the article...

>Gilles Brassard in Montreal has been working on this for a while, and

>has a working prototype...

See Chapter 6 "Quantum Cryptography" in Brassard's book "Modern Cryptolgy",
which is #325 in the Springer-Verlag Lecture Notes in Computer Science series.
A note for the chapter says it "was written with Charles H. Bennett".

Besides having fun stuff like this, the book is a good introduction/survey.
Its ISBNs are: 3-540-96842-3 and 0-387-96842-3.


- Harry Carter (h...@world.std.com)

-- This .sig for rent. No reasonable offer refused! --

Tim Wilkinson

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Jul 9, 1992, 2:31:25 AM7/9/92
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na...@netcom.com (John Nagle) writes:
:
: Scientific American (July 1992, page 100) notes briefly that

It would seem that the UK edition of Scientific American is somewhat
different than the US edition ... it doesn't appear to have the note on the
above device (it only goes upto page 96!). If someone could summaries it
for me I would greatly appreciate it.

Tim
--
Tim Wilkinson E-mail: t...@cs.city.ac.uk
Systems Architecture Research Centre, Fax: +44 71 477 8587
City University, London, UK. Tel: +44 71 477 8551

Clive Feather

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Jul 10, 1992, 6:38:00 AM7/10/92
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In article <1992Jul9.0...@city.cs> t...@cs.city.ac.uk (Tim Wilkinson) writes:
>na...@netcom.com (John Nagle) writes:
>: Scientific American (July 1992, page 100) notes briefly that
>: Charles Bennett at IBM's Watson Research Center has built a device for
>: transmitting a random number safely using the Einstein-Podolsky-Rosen
>: effect.
>It would seem that the UK edition of Scientific American is somewhat
>different than the US edition ... it doesn't appear to have the note on the
>above device (it only goes upto page 96!).

It's on page 78, in the main text, not a box.

Anyone in the US want to compare contents, so we can learn what we're
missing in our edition ?

--
Clive D.W. Feather | IXI Limited | If you lie to the compiler,
cl...@x.co.uk | 62-74 Burleigh St. | it will get its revenge.
Phone: +44 223 462 131 | Cambridge CB1 1OJ | - Henry Spencer
Fax: +44 223 462 132 | United Kingdom |

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