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Quantum Cryptography Conquers Noise Problem
ananyo writes "Quantum-encryption systems that encode signals into a series of single photons have so far been unable to piggyback on existing telecommunications lines because they don't stand out from the millions of others in an optical fiber. But now, physicists using a technique for detecting dim light signals have transmitted a quantum key along 90 kilometers of noisy optical fiber. The feat could see quantum cryptography finally enter the mainstream. The researchers developed a detector that picks out photons only if they strike it at a precise instant, calculated on the basis of when the encoded photons were sent. The team's 'self-differentiating' detector activates for 100 picoseconds, every nanosecond. The weak charge triggered by a photon strike in this short interval would not normally stand out, but the detector measures the difference between the signal recorded during one operational cycle and the signal from the preceding cycle — when no matching photon was likely to be detected. This cancels out the background hum. Using this device, the team has transmitted a quantum key along a 90-kilometer fiber, which also carried noisy data at 1 billion bits per second in both directions — a rate typical of a telecommunications fiber."
Where can I get buy my personal quantum crypto kit?
Tomorrow is another day...
Next thing you know, they'll invent something that will bend light. Oh wait. They already have! It's called a Prism! And next thing you know... hackers will be 'hacking' light by bending it use natural magenetic forces. And cracking that unsafe light transmission, because we all know, light is NOT faster than electrcity....
"transmitted a quantum key along a 90-kilometer fiber, which also carried noisy data at 1 billion bits per second in both directions — a rate typical of a telecommunications fiber."
Telecommunications fiber with a 90km (~50mi.) length would be considered backbone. Typically two fibers are used to send signal in both directions. Single fiber applications require different frequencies of light to both TX & RX. This single fiber application is only used in metro FTTX/GPON situations - never in backbone as the frequency splitting equipment adds relatively high amounts of loss to your signal, impacting how far you can go without regeneration.
Send a handshake message used to calculate transit time, and then another to specify when the next packet will be sent, or at what intervals. If it fails redo the handshake.
love is just extroverted narcissism
My understanding is this would allow you to send bits ensured that nobody else had seen them. But every router / repeater must do exactly that, to send them on the next hop. So really, this is just for when you believe you have one continuous fiber strand and want to make sure... correct? If so it does not allow individuals to communicate securely over the Internet, since there is no un-interrupted strand connecting the endpoints. For a truly private network, like connecting missile launch sites to a command center, or helping a domestic telco ensure its undersea hops aren't being spied on by a foreign power between repeaters, then I can see the utility.
Shouldn't it be more like, quantum tamper detection? It's just using one-time pad in such a way that the pad's transmission getting intercepted will trigger the tamper detection mechanism.
"Screw Sun, cross-platform will never work. Let's move on and steal the Java language." - Visual J++ Product Manager
While the hardware challenges are undoubtedly substantial, the basic idea is just a variation on time division multiplexing, which has been extensively used since the days of the telegraph, well before 1900. If this receives a patent, I hope it is for some hardware advance and not just because of the sharing of the fibre.
no, the safe way would be to synchronized something like a good atomic clock in person, transmit periodically the the drift and sometime a key or a ping using the low energy hidden in plain sight technique
Jehovah be praised, Oracle was not selected
Why would the handshake need to be encrypted?
There are numerous problems:
1. You need _optical_ switches, i.e. switched circuits. That approach failed a long time ago. Anybody remember ATM?
2. 90km is nothing. Amplification is impossible, so unless they reach 10'000km, this is completely irrelevant.
3. Nobody needs it. Cryptography does fine. (No, this is at best "quantum modulation", no crypto involved.) If you are paranoid, use OTPs. They are far, far cheaper, far, far more reliable and completely compatible with existing networks.
4. Remember, this is only key exchange, not actual data transmission. As such it is pretty useless, as you still need to rely on cryptography for the message transfer.
5. The security guarantees are far, far weaker than people are made to believe. Just look at the history of successful compromises.
6. Not even the physics may work out. Quantum theory is a _theory_, not established fact.
Another worthless stunt.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
Why would the handshake need to be encrypted?
You need to securely communicate the handshake, because otherwise the eavesdropper can intercept that message, and increase the transit time to a point long enough that they then will be able to perform a man in the middle attack on the following quantum key distribution packets.
I gotta admit that I'm not familiar with photonic quantum cryptography.
As far as I know, photonics means light, and light does reflect - and could even possibly be diverted (from one beam and splits it into two)
Can the MIM (man in the middle) spit a beam into two, letting the "original" beam to travel to whoever the recipient while working on the "branch"?
Would that approach cause a "noticeable disruption"?
Muchas Gracias, Señor Edward Snowden !
If you're going to have to be together in person anyway, why not just generate/swap keys then..?
which is totally what she said
Supposing I didn't get the message I was expecting to receive, how do I know it wasn't intercepted?
I still don't understand the benefit of Quantum Cryptography - it only prevents eavesdropping on the wire, right? It doesn't prevent a man-in-the-middle (where someone would receive the signal, read it, and retransmit it along the wire)?
Assuming your machine is clean from infection, the big eavesdropping concerns today come from man-in-the-middle attacks: rerouted lan traffic (such as compromised clients running an ARP spoof), and intermediary nodes between endpoints (eg. your ISP, and the Internet backbone routers). The only thing QC prevents (actual, physical wiretapping), as I understand it, is not much of a concern anyways.
Because you want the key to be destroyed in case of eavesdrop. Suppose you swap a 64Gb one time pad with me, what assurance do you have that I did not copy the file to Alice ?
Jehovah be praised, Oracle was not selected