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China Launches World's First Quantum Communications Satellite (theverge.com)
hackingbear quotes a report from The Verge: China's quantum network could soon span two continents, thanks to a satellite launched earlier today. Launched at 1:40pm ET, the Quantum Science Satellite is designed to distribute quantum-encrypted keys between relay stations in China and Europe. When working as planned, the result could enable unprecedented levels of security between parties on different continents. China's new satellite would put that same fiber-based quantum communication system to work over the air, utilizing high-speed coherent lasers to connect with base stations on two different continents. The experimental satellite's payload also includes controllers and emitters related to quantum entanglement. The satellite will be the first device of its kind if the quantum equipment works as planned. According to the Wall Street Journal, the project was first proposed to the European Space Agency in 2001 but was unable to gain funding.
I'm confused, by QM generally, and this in particular.
Is there any military application, or are those guys just going to keep using boring old physical key distribution, and one-time-pads for the serious stuff?
FTFY.
Yes, I would say that secure key distribution has a military application - secure communications.
Good on them I say, pushing the limits further, real science..
Compare that with the reaction of the DNC to their hacked emails, by creating a board of lawyers
and politicos to fix their security problems. I can only assume by pushing for more spying and
monitoring laws, less encryption, and backdoors in everything, because that helps, right?
Face it, the Chinese are rapidly become world technology leaders, and denial wont stop it.
These days it looks like the Chinese are working hard to become the new Renaissance state, while
the west is rushing to emulate the worst of Maoist stats China through totalitarian control and monitoring
of their citizens..
Sad really, but inevitable with a western population that has become too focused on maximising their own
personal comfort, and running in fear at anything that is unfamiliar or uncomfortable - basically ceding total
control to a state that is more than happy to grab it and run. Those in power will be laughing all the way
to the collapse, with little thought to what happens after.
But dont worry, just keep supporting your liberal left, or your religious right, and ignore the fact that both
sides are playing the same gave of totalitarian control at any cost, while the east gets on with actual
production and development.
Here's a human readable primer on it:
http://www.techrepublic.com/blog/it-security/how-quantum-cryptography-works-and-by-the-way-its-breakable/
I've marked the backchannel of extra filtering information with a **** below. You will see this in all Quantum signal experiments. An extra channel of information used to fixup the result. Think about it for a second, you're exchanging KEYS not information, and the KEY exchange itself requires an exchange of a backchannel in a secure way!
How it works for light:
Alice uses a light source to create a photon.
The photon is sent through a polarizer and randomly given one of four possible polarization and bit designations — Vertical (One bit), Horizontal (Zero bit), 45 degree right (One bit), or 45 degree left (Zero bit).
The photon travels to Bob's location.
Bob has two beamsplitters — a diagonal and vertical/horizontal - and two photon detectors.
Bob randomly chooses one of the two beamsplitters and checks the photon detectors.
The process is repeated until the entire key has been transmitted to Bob.
****Bob then tells Alice in sequence which beamsplitter he used.
Alice compares this information with the sequence of polarizers she used to send the key.
Alice tells Bob where in the sequence of sent photons he used the right beamsplitter.
Now both Alice and Bob have a sequence of bits (sifted key) they both know.
---------------------
The assumption is that the attacker cannot see the key exchange message without affecting it by more than a statistical error.
However real world attacks mean you can read the photon and send a similar polarized photon to Bob. In the Swedish attack on this, they sent LOTS of photons, some of which were bound to have the correct polarization, in effect they overwhelmed the detector which has no way of knowing if photons are at both slits because Bob only checks one slit. But an easier attack is to attack the back channel of info. Since Alice keeps sending till she thinks Bob has the full key, an attacker can force her to keep sending till *he* has the key from his choice of photons by intercepting Bobs message back and adding his own mistakes to it.
In the real world fiber optics have repeaters (electrical signal boosters) and QC key exchange does not work.
In the real world fiber optics lose photons, and you cannot send individual photons and reliably receive it at the other end.
Here (the space satellites) it likely also has no purpose, they could not ensure the single 'photon' is sent and received, it would be lost in the atmosphere, so there will be extra fixup signals. You could attack that extra-fixup too in a real world system, as well as the back channel. e.g. man in balloon intercepts the signal and sends a fake signal. He can't generate a real fake signal fast enough, so he generates his own. Did he guess right? No? Send the missing-bit signal and try again. Those sorts of attacks will likely be possible with their real world implementation.
The NSA and about 2 dozen other TLA's have every word of that conversation recorded, transcribed, and analyzed.
vai dar teu cuzinho até engravidar, pra ver se tu tem uma filha com merda na cabeça como você.
So have you been able to mug anyone's gold medal yet?
You do know that China simply steals or buys its way into a lot of technological progress, right? Both the USA and Taiwan have recently arrested people who were happy to pass on secrets of various kinds to their masters in the PRC for money.
But I also am a bit amused that you seem to think that quantum encryption - if they even pull it off - won't be used for bad purposes for the state. Maybe you're not aware of this, but people in China are not allowed Twitter or Facebook accounts because - I kid you not kid - the government is terrified of their possible use to mobilize the masses against the Communist Party. Mark Zuckerburg can suck up to them all he wants and continue to learn Mandarin in his spare time but it's not going to get them to relax their paranoia against a street revolution.
I have a question not directed at you. Let's just say for example that they get this to work. Let's say that for now there is no way to break it. Is there a way to mess with the photons so that even if the encryption can't be broken, nobody on either end can use it for communication because it gets scrambled while going between the 2 sites?
This is for Quantum Key Distribution, right?
Religion is what happens when nature strikes and groupthink goes wrong.
utilizing high-speed coherent lasers to connect with base stations on two different continents
-from TFS
A laser differs from other sources of light in that it emits light coherently.
- From Wikipedia
Lasers also operate at the speed of light (albeit the encoding is slower than that). Me wonders what a llow speed incoherent laser looks like? Maybe signal mirrors? What type of technology is China using? /sarcasm
Silence is a state of mime.
You do know that China simply steals or buys its way into a lot of technological progress, right?
and You do know that the USA simply stole or bought its way into a lot of technological progress too, right?
It's just me or this seems a load of shit?
Achille Talon
Hop!
I suspect the satellite launch has more of political than military purpose. China's economy is going downhill and so it seems is its hopes of Olympic gold, its standing as number 2 (behind US) being threatened: http://www.reuters.com/article...
Who knows, maybe the propaganda bureau decided some good news is in order.
Laser communication between distant satellites is fraught with difficulties.
Lasers have a divergence greater than zero. Over huge distances, this results in a very weak signal at the receiving end.
Lasers exit through an aperture. Diffraction occurs. That spreads the beam, too.
Lasers have speckle, even if the ends of the chamber (gas or solid state) are polished to be atomically smooth. The lasing cavity, you see, is not one-dimensional, resulting in path-length variation for the lasing photons. So, aside from the minor wavelength spread that this induces, it also produces speckle. No one has devised a solution for speckle, nor will they for the next 20 years or so.
I am more excited to see how the communication using QM entanglement works!
If it works (per theory), then there would be nearly zero delay, as communication would not be via EM waves (which travel at the slow speed of light).
Self-importance and self-indulgence is the root of ALL evil.
They are going to screw you and I if Trump does not win, they will feel emboldened for the final strike. The one which will prove deadly.
Tin foil alert! Tin foil alert!