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Australian Gov't May Employ a Homegrown Quantum Key System
mask.of.sanity writes "The Australian government is trialling a new Quantum Key Distribution (QKD) system built by Aussie scientists.
QKD is considered the world's toughest security because the slightest attempt to intercept the one time keys, coded into lasers at the quantum level, will disrupt the beam. The technology differs from current cryptography tech primarily because it's cheap. Well, less than the $US100k price tag of rival systems. It uses off-the-shelf networking gear instead of proprietary technology, and is built on open standards, so it's easier to install. The random key is encoded at the quantum level in the sidebeam in the phase and amplitude, or brightness and colour, of a highly tuned laser beam. The creators, who built the system in part for their Ph.Ds, said it can be used to transport the most sensitive data like critical infrastructure and secret commercial IP. The days of hand-delivered security keys are numbered."
In general I think that although standard key exchange methods are theoretically less secure than quantum key exchanges, at least the standard key exchange methods are a) well understood, b) tested and c) commercially supported.
Putting highly secret documents in the hands of a technology made by college students working on PHD thesis seems to be a premature use of this technology.
It's not the technology itself, but the implementation of the technology that I'd worry about. And cost doesn't seem to be a good reason to take a gamble.
So... are the scientists that frustrated with the Aussie internet filter that they're employing a quantum key encryption system just so they can get their porn?
greed@All_Evils:~#
"That's not encryption. THIS, now THIS is encryption."
Please help metamoderate.
Worse than that. The quantum stuff is really cool, and all kinds of useful for making sure a given bit of fiber isn't being eavesdropped on; but it is only link-level security. You have to have a run of fiber directly between hither and yon for communications to be secure. With ordinary crypto, you can use public internet or untrusted network segments controlled by others, or bailing wire or whatever. That is the ultimate limitation.
I hear that the technology is called "Key Order Assignment by Laser Application".
Last I heard, quantum cryptography did require a dedicated line. And you can't intercept and regenerate the signal because the laws of quantum physics make it impossible to measure enough information about the beam to generate a copy of it. The way quantum cryptography works (at least this is one simple scheme), the sender of the key transmits photons that are polarized in one of 4 directions: N-S, E-W, NE-SW, or NW-SE. But when you measure the photons, you have to choose whether to make a N-S vs. E-W measurement, or an NE-SW vs. NW-SE measurement - you can't make both. And if you choose the wrong one for any particular photon, the outcome of the measurement is random (and the original orientation of the photon is lost). Although, the sender and receiver of the key will have to compare notes via non-quantum means, to see which photons they measured using the same scheme, and if you have access to both the quantum channel and the non-quantum channel, I guess you could pull off a man-in-the-middle attack.
They will encrypt their thesis with it. If ever decrypted, their doctorates will be revoked!
I am at a loss to understand why the Australian Government would want this standard of security. This requires a dedicated fibre so it only works over a short range and over a land line. The bulk of security issues would be with international communications (say diplomatic stuff), wireless communications (police, military etc) and office networks (the federal public service).
But quantum won't help you in any of those cases. Oh well. I doubt I will hear if it is ever actually used.
http://michaelsmith.id.au
Exactly. Is public key crypto broken enough to need to spend any money to switch over to QKD? For that matter is public key crypto over the internet broken?
Yes. Think secret plans that can't get out, even in 20 years time.
Can you guarantee quantum computers won't be around in 20 years time?
No, from what I understand the system involves strapping a key to a shark who'll swim it to the recipient. The friggin' laser shoots anyone trying to intercept it, thereby guaranteeing security.
Sharks with friggin laser beams have become more adundant as of late, which is why they can do this so cheaply.
The key is not encoded -- it is random. Both the "sender" and receiver have no idea what the photon's characteristics are. They both flip coins to see which type of measurement to make. Then they keep the bits where they made the same type of measurement and throw away the others.
Any intermediate party will either receive the photon (so the receiver won't) or not receive the photon (and can't measure it). Further, no intermediate party knows what measurements the sender and receiver will make so they can't make the same measurements. If the intermediary can't make the same measurements then it can't generate the same key, and can't generate a passable photon for the receiver. Assuming the sender and receiver have another channel which is secure against man in the middle attacks (though not necessarily secure against eavesdroppers), they can tell each other which type of measurements they made and know what to keep.
Yes, but like any quantum cryptography method, it's still vulnerable to a SITM (Shark In The Middle) attack.
Rampant carbon sequestration destroyed the Dinosaurs' tropical paradise. I'm here to help repair the damage.
Professor Farnsworth: No fair! You changed the outcome by measuring it!
http://futurama.wikia.com/wiki/The_Luck_of_the_Fryrish
Homonyms are fun!
You're driving your car, but they're riding their bikes there.
I suspect we differ on the definition of "intercept". If you strictly mean "capture and extract information from", then I agree. Any measurement (the "extract information" part) will collapse the wavefunction, destroying the quantum coherences and ultimately (with approaching-unity probability) being detected by the QKD scheme. However, I was using the term in the more general sense of "have some device between", in which case what I said is entirely correct. Here's why:
I'm well versed in the no-cloning theorem. As such, I know why it doesn't apply here. The no-cloning theorem is in relation to making an identical and independent copy of any (a general) quantum system whilst retaining the original system. In this context it would amount to producing a duplicate signal, independent but equal to the original signal. This is not possible under the no-cloning theorem. (I'll preempt a point here, too: Entanglement is not cloning, although it can sometimes look similar.)
But, intercepting and regenerating the signal does not necessarily involve ever having both the original and regenerated signals existing at the same time. Take an example of a kind of quantum repeater, a device that converts a photon signal into some other quantum state, say electron spin, and then converts that spin into a new photon signal. It's roughly the same idea as classical repeaters in long-distance fibre-optic communications. Now, I consider this operation to be an interception of the signal and generation of a new signal with the same information. It's a coherent process; all the quantum information in the original signal remains intact. But you can't get back the photons from the original signal, so the no-cloning theorem is not relevant. (A more detailed explanation of the workings of a quantum repeater could include entanglement, which also means no-cloning theorem is not relevent.)
A restriction on the device is that, to function, it cannot collapse the wavefunction. That means that (at a minimum) it cannot make a projective measurement of the quantum state. Thus, it cannot make any recorded measurement on the state, because that would require making a projective measurement, which would require defining a projection basis (randomly(!), because there's no better way), which would collapse the wavefunction, which would rightly end up being detected by the QKD scheme as eavesdropping.
So, you can have a device which intercepts and regenerates the signal, you just can't ask it any questions.
Guess where a great deal of the US's intelligence data is collected from. Hint: it's a large, dry country within long-range radio distance from China.
Guess where that data gets transmitted back to the US from? Hint: several top-secret joint US-Australian bases located in various places in Central Australia (i.e. the middle of nowhere)
And guess which country has more access to intelligence sharing with the US than any other allied nation (except for the UK)?
Australia's geographic position means a LOT of US intelligence data either is sourced from here or flows through here. So it's in all allied countries interests to have good encryption here ;)
Some puns are just unbearable. Tim S
Quantum leap: (adj.) literally, to move by the smallest amount theoretically possible. In advertising, to move by the largest leap imaginable (in the mind of the advertiser). There is no contradiction.
- Tonkin's First Computer Dictionary
"It doesn't cost enough, and it makes too much sense."
Quantum leap: (adj.) literally, to move by the smallest amount theoretically possible. In advertising, to move by the largest leap imaginable (in the mind of the advertiser). There is no contradiction.
- Tonkin's First Computer Dictionary
"Quantum Leap": (1989) Scientist Sam Beckett finds himself trapped in time--"leaping" into the body of a different person in a different time period each week.
- The Internet Movie Database
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