| Topic: |
Science > Physics |
| User: |
"Sam Wormley" |
| Date: |
10 May 2005 10:37:45 PM |
| Object: |
Quantum cryptography tackles video |
Quantum cryptography tackles video
http://physicsweb.org/articles/news/9/5/5/1
10 May 2005
Physicists at Toshiba have used quantum cryptography to transmit voice
and video over a secure optical fibre link. The demonstration is
significant because it shows that the single-photon encryption
technology is compatible with real Internet Protocol (IP) traffic and
also robust enough for deployment on commercial optical fibre networks.
The system was shown to financial institutions and government
representatives in London by Andrew Shields and colleagues from Toshiba
Research Europe in Cambridge.
See: http://physicsweb.org/articles/news/9/5/5/1
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| User: "Jan Panteltje" |
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| Title: Re: Quantum cryptography tackles video |
11 May 2005 08:30:20 AM |
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On a sunny day (Wed, 11 May 2005 03:37:45 GMT) it happened Sam Wormley
<swormley1@mchsi.com> wrote in <d6fge.73586$c24.66093@attbi_s72>:
Quantum cryptography tackles video
http://physicsweb.org/articles/news/9/5/5/1
10 May 2005
Physicists at Toshiba have used quantum cryptography to transmit voice
Yes, it was discussed in sci.crypt weeks ago, and it is useless, as it
requires a glassfiber between receiver and transmitter, and STILL a man in
the middle can fake it.
So you need a reel of fiber, and a shovel, and a permit to open up every
street etc...
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| User: "Baugh" |
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| Title: Re: Quantum cryptography tackles video |
11 May 2005 11:31:25 AM |
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Jan Panteltje wrote:
On a sunny day (Wed, 11 May 2005 03:37:45 GMT) it happened Sam Wormley
<swormley1@mchsi.com> wrote in <d6fge.73586$c24.66093@attbi_s72>:
Quantum cryptography tackles video
http://physicsweb.org/articles/news/9/5/5/1
10 May 2005
Physicists at Toshiba have used quantum cryptography to transmit voice
Yes, it was discussed in sci.crypt weeks ago, and it is useless, as it
requires a glassfiber between receiver and transmitter, and STILL a man in
the middle can fake it.
So you need a reel of fiber, and a shovel, and a permit to open up every
street etc...
You are mistaken. The point of quantum crypt. is that should the man
in the middle read the signal he will affect it. You can't anonymously
tap a quantum signal.
Regards,
James Baugh
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| User: "Schoenfeld" |
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| Title: Re: Quantum cryptography tackles video |
11 May 2005 01:59:01 PM |
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Baugh wrote:
Jan Panteltje wrote:
On a sunny day (Wed, 11 May 2005 03:37:45 GMT) it happened Sam
Wormley
<swormley1@mchsi.com> wrote in <d6fge.73586$c24.66093@attbi_s72>:
Quantum cryptography tackles video
http://physicsweb.org/articles/news/9/5/5/1
10 May 2005
Physicists at Toshiba have used quantum cryptography to transmit
voice
Yes, it was discussed in sci.crypt weeks ago, and it is useless, as
it
requires a glassfiber between receiver and transmitter, and STILL a
man in
the middle can fake it.
So you need a reel of fiber, and a shovel, and a permit to open up
every
street etc...
You are mistaken. The point of quantum crypt. is that should the man
in the middle read the signal he will affect it. You can't
anonymously
tap a quantum signal.
Quantum Cryptography will only be used for secure key exchange. It's
still not 100% secure.
Regards,
James Baugh
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| User: "Baugh" |
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| Title: Re: Quantum cryptography tackles video |
11 May 2005 05:42:44 PM |
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Schoenfeld wrote:
Baugh wrote:
Jan Panteltje wrote:
On a sunny day (Wed, 11 May 2005 03:37:45 GMT) it happened Sam
Wormley
<swormley1@mchsi.com> wrote in <d6fge.73586$c24.66093@attbi_s72>:
Quantum cryptography tackles video
http://physicsweb.org/articles/news/9/5/5/1
10 May 2005
Physicists at Toshiba have used quantum cryptography to transmit
voice
Yes, it was discussed in sci.crypt weeks ago, and it is useless, as
it
requires a glassfiber between receiver and transmitter, and STILL a
man in
the middle can fake it.
So you need a reel of fiber, and a shovel, and a permit to open up
every
street etc...
You are mistaken. The point of quantum crypt. is that should the man
in the middle read the signal he will affect it. You can't
anonymously
tap a quantum signal.
Quantum Cryptography will only be used for secure key exchange. It's
still not 100% secure.
Yes but with a quantum crypto line you can send arbitrarily large keys
with assurance that they have not been intercepted. Hence via *private*
key encryption you can get as close to 100% secure as possible.
Of course this will help naught if the people at the end points are
given a big enough bribe.
So the endevor is worth while. It is IMNSHO all the practical benefit
we will get out of the domain of "quantum computing". But that is a
guess on my part.
Regards,
James Baugh
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| User: "Schoenfeld" |
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| Title: Re: Quantum cryptography tackles video |
11 May 2005 06:49:16 PM |
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Baugh wrote:
Schoenfeld wrote:
Baugh wrote:
Jan Panteltje wrote:
On a sunny day (Wed, 11 May 2005 03:37:45 GMT) it happened Sam
Wormley
<swormley1@mchsi.com> wrote in <d6fge.73586$c24.66093@attbi_s72>:
Quantum cryptography tackles video
http://physicsweb.org/articles/news/9/5/5/1
10 May 2005
Physicists at Toshiba have used quantum cryptography to transmit
voice
Yes, it was discussed in sci.crypt weeks ago, and it is useless,
as
it
requires a glassfiber between receiver and transmitter, and STILL
a
man in
the middle can fake it.
So you need a reel of fiber, and a shovel, and a permit to open up
every
street etc...
You are mistaken. The point of quantum crypt. is that should the
man
in the middle read the signal he will affect it. You can't
anonymously
tap a quantum signal.
Quantum Cryptography will only be used for secure key exchange.
It's
still not 100% secure.
Yes but with a quantum crypto line you can send arbitrarily large
keys
with assurance that they have not been intercepted. Hence via
*private*
key encryption you can get as close to 100% secure as possible.
Of course this will help naught if the people at the end points are
given a big enough bribe.
There's another fundamental problem which I have not seen discussed
anywhere. The only practical benefit of a quantum line is that the two
parties can detect evesdroppers (since the evesdropper affects the
polarity of the transmitted photons). Thus the idea is that the
communicating parties won't transmit data over the classical line if
they detect an evesdropper on the quantum line (since the advesary
would know the key and thus be able to decrypt the data).
But this protocol allows advesaries to simply packet sniff the quantum
line for the intent of preventing communications between the two
parties.
Whats worse, private communications exposed to advesaries or advesaries
preventing private communications completely?
So the endevor is worth while. It is IMNSHO all the practical
benefit
we will get out of the domain of "quantum computing". But that is a
guess on my part.
Regards,
James Baugh
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| User: "Baugh" |
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| Title: Re: Quantum cryptography tackles video |
12 May 2005 02:21:16 PM |
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Schoenfeld wrote:
But this protocol allows advesaries to simply packet sniff the quantum
line for the intent of preventing communications between the two
parties.
Whats worse, private communications exposed to advesaries or advesaries
preventing private communications completely?
But that hasn't changed anything, you can simply cut the line instead of
tapping it. Point is that you can't tap the line without cutting it.
James
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| User: "Schoenfeld" |
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| Title: Re: Quantum cryptography tackles video |
12 May 2005 03:36:06 PM |
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Baugh wrote:
Schoenfeld wrote:
But this protocol allows advesaries to simply packet sniff the
quantum
line for the intent of preventing communications between the two
parties.
Whats worse, private communications exposed to advesaries or
advesaries
preventing private communications completely?
But that hasn't changed anything, you can simply cut the line instead
of
tapping it. Point is that you can't tap the line without cutting it.
One should not forget the wave property of light. It should be easier
to jam a quantum line than a classical line.
James
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| User: "Jan Panteltje" |
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| Title: Re: Quantum cryptography tackles video |
12 May 2005 05:27:17 PM |
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On a sunny day (12 May 2005 13:36:06 -0700) it happened "Schoenfeld"
<schoenfeld1@gmail.com> wrote in
<1115930166.652817.182420@g44g2000cwa.googlegroups.com>:
Baugh wrote:
Schoenfeld wrote:
But this protocol allows advesaries to simply packet sniff the
quantum
line for the intent of preventing communications between the two
parties.
Whats worse, private communications exposed to advesaries or
advesaries
preventing private communications completely?
But that hasn't changed anything, you can simply cut the line instead
of
tapping it. Point is that you can't tap the line without cutting it.
One should not forget the wave property of light. It should be easier
to jam a quantum line than a classical line.
From a technical point of view, I think not.
I have designed some systems that used coax to transfer multiplexed data.
These were tested (for acceptance) by putting something like 1kV pulses on
the outside, then looking if the signal got screwed up, or any hardware damaged.
You will not believe how much signal gets through, 40dB demping is only 100x,
that still leaves 1000 / 100 = 10 V!
On an optical line, I am not so sure how you will even get to the fiber in
question without physically cutting the cable open, and then inserting
extra photons via the outside?
Glassfiber is really not that sensitive, but I have not tried that one.
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| User: "Baugh" |
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| Title: Re: Quantum cryptography tackles video |
12 May 2005 04:26:57 PM |
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Schoenfeld wrote:
One should not forget the wave property of light. It should be easier
to jam a quantum line than a classical line.
Sure, but both are easy, get a pair of wire cutters and "snip".
If your just being malicious then its easy.
The point is to deter the greedy not the malicious.
Malice is usually less rationally motivate than greed.
And thus the inventiveness and effectiveness of the greedy
is greater.
For all the damage caused by two airliners crashing into the WTC
consider the annual effect the illegal drug trade has on the US.
Who's winning *that* war?
So as a business, if you can prevent the thief from profiting by
his action why will he bother?
Regards,
James Baugh
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| User: "Schoenfeld" |
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| Title: Re: Quantum cryptography tackles video |
12 May 2005 06:15:56 PM |
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Baugh wrote:
Schoenfeld wrote:
One should not forget the wave property of light. It should be
easier
to jam a quantum line than a classical line.
Sure, but both are easy, get a pair of wire cutters and "snip".
If your just being malicious then its easy.
The point is to deter the greedy not the malicious.
Malice is usually less rationally motivate than greed.
And thus the inventiveness and effectiveness of the greedy
is greater.
For all the damage caused by two airliners crashing into the WTC
consider the annual effect the illegal drug trade has on the US.
Who's winning *that* war?
So as a business, if you can prevent the thief from profiting by
his action why will he bother?
Regards,
James Baugh
Sure, but you should consider how DoS attacks have evolved using an
analogous vulnerability of the IP protocol. If people can likewise jam
quantum lines with relative ease then they most assuredly will. Unless
there is a way to protect against this then it will be a serious
problem.
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| User: "Jan Panteltje" |
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| Title: Re: Quantum cryptography tackles video |
11 May 2005 03:48:12 PM |
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On a sunny day (Wed, 11 May 2005 12:31:25 -0400) it happened Baugh
<baconbaugh@charter.net> wrote in <Grqge.3571$sV7.2740@fe02.lga>:
Jan Panteltje wrote:
On a sunny day (Wed, 11 May 2005 03:37:45 GMT) it happened Sam Wormley
<swormley1@mchsi.com> wrote in <d6fge.73586$c24.66093@attbi_s72>:
Quantum cryptography tackles video
http://physicsweb.org/articles/news/9/5/5/1
10 May 2005
Physicists at Toshiba have used quantum cryptography to transmit voice
Yes, it was discussed in sci.crypt weeks ago, and it is useless, as it
requires a glassfiber between receiver and transmitter, and STILL a man in
the middle can fake it.
So you need a reel of fiber, and a shovel, and a permit to open up every
street etc...
You are mistaken. The point of quantum crypt. is that should the man
in the middle read the signal he will affect it. You can't anonymously
tap a quantum signal.
Wrong, the way it works is that they generate a key, use OTP (one time pad),
and xor the data with it.
The key is send via the fiber, as polarized photon pairs, so if A measures
one polarization, B must have the other.
HOWEVER one can buy these units commercially, cut the fiber, decode, fix the
data, then re-encode (generate a new pair of photons).
The ONLY thing protecting you against that attack is a strict protocol, NOT
the quantum stuff.
Look it up, sci.crypt, about 2 weeks ago.
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| User: "Baugh" |
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| Title: Re: Quantum cryptography tackles video |
11 May 2005 06:50:04 PM |
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Jan Panteltje wrote:
On a sunny day (Wed, 11 May 2005 12:31:25 -0400) it happened Baugh
<baconbaugh@charter.net> wrote in <Grqge.3571$sV7.2740@fe02.lga>:
Baugh:
You are mistaken. The point of quantum crypt. is that should the man
in the middle read the signal he will affect it. You can't anonymously
tap a quantum signal.
Wrong, the way it works is that they generate a key, use OTP (one time pad),
and xor the data with it.
The key is send via the fiber, as polarized photon pairs, so if A measures
one polarization, B must have the other.
HOWEVER one can buy these units commercially, cut the fiber, decode, fix the
data, then re-encode (generate a new pair of photons).
The ONLY thing protecting you against that attack is a strict protocol, NOT
the quantum stuff.
Look it up, sci.crypt, about 2 weeks ago.
Pardon, I didn't read the article. I did attend a couple of seminars on
the issue. I don't know if this is a case of what I was explained but
the point of the method is that the pair is entangled.
This means given two sets of polarization measurements, vert vs horiz.
and l-cir vs r-circ, All corresponding pair mesurements will be
correlated. However if you intercept one of the pair and measure one
of the polarization modes (say linear) you cannot use that to replicate
the that half of an entangled pair. You can reproduce the linear value
but the circular polarization is now no-longer correlated with that
of the other of the pair.
The critical point is that what you can measure and then reproduce
(tapping the line) is mode dependent (circular vs linear polarization,
or x-spin vs y-spin vs z-spin), but the entanglement correlates all
modes (or anti-correlates which comes to the same thing). This stronger
correlation is at the cost of any actual control of which the values
are. Thus one side doesn't actually send the other a specific signal,
they both observe the same modes of an entangled pair and get private
access to the random outcomes.
You could only tap the line if you knew ahead of time which modes the
two listners would choose to observe. By using a true random number
generator and the values of previous bits to decide the next they can
establish a protocol only if you aren't listening to the majority of the
bits. Their failure is their detection of a tapped line. Their success
assures that you've not been listening to enough of the signal to get
the full key. This is a bit simplified but that is the essence of the
method.
Regards,
James Baugh
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| User: "Jan Panteltje" |
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| Title: Re: Quantum cryptography tackles video |
12 May 2005 01:41:11 PM |
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On a sunny day (Wed, 11 May 2005 19:50:04 -0400) it happened Baugh
<baconbaugh@charter.net> wrote in <NSwge.7744$fY4.2267@fe07.lga>:
Jan Panteltje wrote:
On a sunny day (Wed, 11 May 2005 12:31:25 -0400) it happened Baugh
<baconbaugh@charter.net> wrote in <Grqge.3571$sV7.2740@fe02.lga>:
Baugh:
You are mistaken. The point of quantum crypt. is that should the man
in the middle read the signal he will affect it. You can't anonymously
tap a quantum signal.
Wrong, the way it works is that they generate a key, use OTP (one time pad),
and xor the data with it.
The key is send via the fiber, as polarized photon pairs, so if A measures
one polarization, B must have the other.
HOWEVER one can buy these units commercially, cut the fiber, decode, fix the
data, then re-encode (generate a new pair of photons).
The ONLY thing protecting you against that attack is a strict protocol, NOT
the quantum stuff.
Look it up, sci.crypt, about 2 weeks ago.
Pardon, I didn't read the article. I did attend a couple of seminars on
the issue. I don't know if this is a case of what I was explained but
the point of the method is that the pair is entangled.
This means given two sets of polarization measurements, vert vs horiz.
and l-cir vs r-circ, All corresponding pair mesurements will be
correlated. However if you intercept one of the pair and measure one
of the polarization modes (say linear) you cannot use that to replicate
the that half of an entangled pair. You can reproduce the linear value
but the circular polarization is now no-longer correlated with that
of the other of the pair.
The critical point is that what you can measure and then reproduce
(tapping the line) is mode dependent (circular vs linear polarization,
or x-spin vs y-spin vs z-spin), but the entanglement correlates all
modes (or anti-correlates which comes to the same thing). This stronger
correlation is at the cost of any actual control of which the values
are. Thus one side doesn't actually send the other a specific signal,
they both observe the same modes of an entangled pair and get private
access to the random outcomes.
You could only tap the line if you knew ahead of time which modes the
two listners would choose to observe. By using a true random number
generator and the values of previous bits to decide the next they can
establish a protocol only if you aren't listening to the majority of the
bits. Their failure is their detection of a tapped line. Their success
assures that you've not been listening to enough of the signal to get
the full key. This is a bit simplified but that is the essence of the
method.
Regards,
James Baugh
OK, I think I sort of get what you are trying to say.
But this is referred to as 'shared secret'.
In such case you could just as well give both sides a DVD with
'pure random data' and do an OTP.
A lot simpler, and in both cases only the 'shared secret' need to be protected.
Main reason against OTP is key security, now you have the same thing?
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| User: "Baugh" |
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| Title: Re: Quantum cryptography tackles video |
12 May 2005 02:26:11 PM |
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Jan Panteltje wrote:
On a sunny day (Wed, 11 May 2005 19:50:04 -0400) it happened Baugh
<baconbaugh@charter.net> wrote in <NSwge.7744$fY4.2267@fe07.lga>:
Jan Panteltje wrote:
On a sunny day (Wed, 11 May 2005 12:31:25 -0400) it happened Baugh
<baconbaugh@charter.net> wrote in <Grqge.3571$sV7.2740@fe02.lga>:
Baugh:
You are mistaken. The point of quantum crypt. is that should the man
in the middle read the signal he will affect it. You can't anonymously
tap a quantum signal.
Wrong, the way it works is that they generate a key, use OTP (one time pad),
and xor the data with it.
The key is send via the fiber, as polarized photon pairs, so if A measures
one polarization, B must have the other.
HOWEVER one can buy these units commercially, cut the fiber, decode, fix the
data, then re-encode (generate a new pair of photons).
The ONLY thing protecting you against that attack is a strict protocol, NOT
the quantum stuff.
Look it up, sci.crypt, about 2 weeks ago.
Pardon, I didn't read the article. I did attend a couple of seminars on
the issue. I don't know if this is a case of what I was explained but
the point of the method is that the pair is entangled.
This means given two sets of polarization measurements, vert vs horiz.
and l-cir vs r-circ, All corresponding pair mesurements will be
correlated. However if you intercept one of the pair and measure one
of the polarization modes (say linear) you cannot use that to replicate
the that half of an entangled pair. You can reproduce the linear value
but the circular polarization is now no-longer correlated with that
of the other of the pair.
The critical point is that what you can measure and then reproduce
(tapping the line) is mode dependent (circular vs linear polarization,
or x-spin vs y-spin vs z-spin), but the entanglement correlates all
modes (or anti-correlates which comes to the same thing). This stronger
correlation is at the cost of any actual control of which the values
are. Thus one side doesn't actually send the other a specific signal,
they both observe the same modes of an entangled pair and get private
access to the random outcomes.
You could only tap the line if you knew ahead of time which modes the
two listners would choose to observe. By using a true random number
generator and the values of previous bits to decide the next they can
establish a protocol only if you aren't listening to the majority of the
bits. Their failure is their detection of a tapped line. Their success
assures that you've not been listening to enough of the signal to get
the full key. This is a bit simplified but that is the essence of the
method.
Regards,
James Baugh
OK, I think I sort of get what you are trying to say.
But this is referred to as 'shared secret'.
In such case you could just as well give both sides a DVD with
'pure random data' and do an OTP.
A lot simpler, and in both cases only the 'shared secret' need to be protected.
Main reason against OTP is key security, now you have the same thing?
Except you can't copy the key without someone knowing. Knowing this
then the key won't be used, another will be generated, until both sides
can know to arbritrary degree of certainty that they have a secure key.
If that's what's being done in this case.
Regards,
James Baugh
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| User: "Raymond Yohros" |
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| Title: Re: Quantum cryptography tackles video |
11 May 2005 01:55:48 AM |
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the simplest posibl way to dearange
data without ever increasing its size
it's d best way 2 go.
creative encryption.
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