Re: quantum hype

2003-10-03 Thread Peter Fairbrother
[EMAIL PROTECTED] wrote: From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Dave Howe Peter Fairbrother may well be in possession of a break for the QC hard problem - his last post stated there was a way to clone photons with high accuracy in retention of their polarization

Re: quantum hype

2003-09-28 Thread Peter Fairbrother
I promised some links about the 5/6 cloning figure. You've had a few experimental ones, here are some theory ones. Cloning machines: http://www.fi.muni.cz/usr/buzek/mypapers/96pra1844.pdf Theoretically optimal cloning machines: http://www.gap-optique.unige.ch/Publications/Pdf/PRL02153.pdf 1/6

Re: quantum hype

2003-09-24 Thread Greg Troxel
I'm always stuck on that little step where Alice tells Bob what basis she used for each photon sent. Tells him how? They need integrity protection and endpoint authentication for N bits of basis. Is the quantum trick converting those N bits to N/2 privacy-protected bits really as

Re: quantum hype

2003-09-22 Thread Jaap-Henk Hoepman
I always understood that QKD is based on a hard problem of which the theory of physics says it is impossible to find a solution (if not, then i'd like to know). Then if QKD breaks, the current theory of physics was wrong. On the other hand, if DH or RSA breaks, factoring or the discrete log turn

RE: quantum hype

2003-09-22 Thread Michael_Heyman
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Dave Howe Peter Fairbrother may well be in possession of a break for the QC hard problem - his last post stated there was a way to clone photons with high accuracy in retention of their polarization [SNIP] Not a break at all. The

Re: quantum hype

2003-09-22 Thread Peter Fairbrother
[EMAIL PROTECTED] wrote: From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Dave Howe Peter Fairbrother may well be in possession of a break for the QC hard problem - his last post stated there was a way to clone photons with high accuracy in retention of their polarization

Re: quantum hype

2003-09-22 Thread Matt Crawford
BTW, you can decrease the wavelength of a photon by bouncing it off moving mirrors. Sure. To double the energy (halve the wavelength), move the mirror at 70% of the speed of light. And since you don't know exactly when the photon is coming, keep it moving at that speed ...

Re: quantum hype

2003-09-21 Thread Arnold G. Reinhold
At 6:38 PM -0400 9/18/03, John S. Denker wrote: Yes, Mallory can DoS the setup by reading (and thereby trashing) every bit. But Mallory can DoS the setup by chopping out a piece of the cable. The two are equally effective and equally detectable. Chopping is cheaper and easier. Other

Re: quantum hype

2003-09-21 Thread Peter Fairbrother
There are lots of types of QC. I'll just mention two. In classic QC Alice generates polarised photons at randomly chosen either + or x polarisations. Bob measures the received photons using a randomly chosen polarisation, and tells Alice whether the measurement polarisation he chose was + or x,

Re: quantum hype

2003-09-21 Thread Dave Howe
no. its the underlieing hard problem for QC. If there is a solution to any of the Hard Problems, nobody knows about them. right, so it's no better than the arguable hard problem of factoring a 2048 bit number. Peter Fairbrother may well be in possession of a break for the QC hard problem - his

Re: quantum hype

2003-09-21 Thread Andreas Gunnarsson
On Sun, Sep 21, 2003 at 01:37:21PM +0100, Peter Fairbrother wrote: [cloning photons] There is also another less noisy cloning technique which has recently been done in laboratories, though it doubles the photon's wavelength, which would be noticeable, To get rid of the wavelength change it

Re: quantum hype

2003-09-20 Thread R. Hirschfeld
Date: Fri, 19 Sep 2003 11:57:22 -0400 From: Ian Grigg [EMAIL PROTECTED] If I understand this correctly, this is both an eavesdropping scenario and an MITM scenario. In the above, Eve is acting as Mallory, as she is by definition intercepting the bits and re- sending them on? As Dave

Re: quantum hype

2003-09-16 Thread John Lowry
QC is currently a one-time pad distribution mechanism - or at lower rates a key establishment mechanism most suitable for symmetric algorithms. You are correct that authentication is not inherent. Then again, this is also true for classical symmetric and PKI schemes. To be usable, all crypto

Re: quantum hype

2003-09-15 Thread Ed Gerck
martin f krafft wrote: So MagiQ and others claim that the technology is theoretically unbreakable. How so? If I have 20 bytes of data to send, and someone reads the photon stream before the recipient, that someone will have access to the 20 bytes before the recipient can look at the 20

Re: quantum hype

2003-09-14 Thread David Wagner
Arnold G. Reinhold wrote: I think there is another problem with quantum cryptography. Putting aside the question of the physical channel, there is the black box at either end that does all this magical quantum stuff. One has to trust that black box. - Its design has to thoroughly audited and

Re: quantum hype

2003-09-13 Thread David Wagner
martin f krafft wrote: So MagiQ and others claim that the technology is theoretically unbreakable. How so? If I have 20 bytes of data to send, and someone reads the photon stream before the recipient, that someone will have access to the 20 bytes before the recipient can look at the 20 bytes,

Re: quantum hype

2003-09-13 Thread martin f krafft
also sprach David Wagner [EMAIL PROTECTED] [2003.09.13.2306 +0200]: You're absolutely right. Quantum cryptography *assumes* that you have an authentic, untamperable channel between sender and receiver. The standard quantum key-exchange protocols are only applicable when there is some other

Re: quantum hype

2003-09-13 Thread David Wagner
On 09/13/2003 05:06 PM, David Wagner wrote: Quantum cryptography *assumes* that you have an authentic, untamperable channel between sender and receiver. Not true. The signal is continually checked for tampering; no assumption need be made. Quantum crypto only helps me exchange a key