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Scientists Race To Establish the First Links of a 'Quantum Internet'
ananyo writes "Two teams of researchers — once rivals, now collaborators — are racing to use the powers of subatomic physics to create a super-secure global communication network. The teams — one led by Jian-Wei Pan at the University of Science and Technology of China, the other by his former PhD supervisor Anton Zeilinger of the University of Vienna — have spent the last 7 years beating each other's distance records for long-distance quantum-teleportation. They now plan to create the first intercontinental quantum-secured network, connecting Asia to Europe by satellite."
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The word "US" is nowhere in sight.. Asia and Europe.. Why am I not surprised?
Because we have always been at war with Eurasia.
Because Quantum Entanglement is not in the bible.
Obama's legacy: (N)othing (S)ecure (A)nywhere and (T)error (S)imulation (A)dministration
Does evesdropping on a quantum message destroy the message? People talk about super secure quantum messages because it leaves a detectable trace, but does it also destroy the message in the process?
Some people die at 25 and aren't buried until 75. -Benjamin Franklin
You and a friend put one black and one white marble in a tin and shake. Without looking you each grab a marble and put it in your pocket. You travel some distance apart and then check your pocket. If your marble is white you now instantly know your friends marble is black. That's basically the level of communication in quantum entanglement.
Probably because quantum entanglement can't actually transmit information
You should re-read that. Quantum entanglement cannot be used for faster than light communication, but that doesn't mean there are not applications in transmitting information slower than speed of light. There definitely are some potential applications in that case, and it is more of a matter if it can be done practically.
Someone else looking at the marbles breaks the entanglement in the quantum case, and you can't copy it before looking. If you tell your friend you got the white marble, and they see a white marble too, they know someone has been at their marbles. Then they know the key is not safe to use. The actual exchange is a little more complicated so you can't work out the key from the classical communication, only the researchers can tell if it has been seen or not. Classically, if you wanted to stop someone from seeing your marbles, I would recommend pants.
Pardon my ignorance, but are you implying that "patents half the shit patented each year" and "invents half the shit invented each year" are the same thing?
Actually, in a practical system, quantum teleportation would generally be used to exchange an entangled photon from which a key can be extracted, the data would sent later using a classical communication technique (like the internet) using classical symmetric encryption scheme (say, like AES-CBC). Of course if the message is small enough, you might just transport the message entangled (instead of just a way to key the encrypted message), but that's much less efficient using current QM entanglement techniques***.
Today key exchange is often done with public-private keys, but the mathematical techniques behind them rely on "trap-door" functions (functions that are relatively easy to compute, but much harder to invert). Hard != impossible, so something that is merely hard to invert today, might be easy in the future. With a quantum key exchange scheme you don't transmit the key, only an entangled photon. Thus can't invert it (with currently known physics), and you can't even intercept it (w/o being detected), so it's impossible to deduce the key even in the future. Of course you could always resort to older time-tested techniques like this...
The reason they need the satellite is to transmit the entangled photon (which is used to extract the key). A classical communications channel is effectively a cascade of store-and-forward (every amplifier and digital buffer along the way) so that every stage is making an "observation" and collpasing the quantum state. You basically want to convey the exact same photon you entangled so that the other side can receive it w/o the communication channel observing it in transit. Ideally, you'd bounce a batch of entangled photon off a satellite and the receiver gets the same photons you sent on the other side. Then both sides extract a key from their respective batch of entangled photons and use that key to exchange the message.
Of course, in a fancier system you might use that one entangled photon to quantum teleport some entangled qubits, but that would be more complicated.
***With current QM techniques, you don't really encode a pre-chosen key by somehow "entangling" it into a photon, you are basically creating a type of mind-meld (entanglement) of two photons in a way so that a quantum measurement made on one correlate with the other. With this, magically each side can extract the same information from their respective entangled photons meaning the same bit of information emerges from these measurements. That is why if someone intercepts the photon and retransmit it, both sides would know because they are unlikely have extracted the same bits from the measurments because with currently known physics it's not possible to observe and exactly recreate a quantum state (although apparently you can teleport it). If that doesn't make sense, it's because QM is not supposed to make sense, it just is (or maybe I'm not explaining it very well).
I can start making Schrodinger's Lolcats. Until you open the link, you don't know if its funny or not.
I still have more fans than freaks. WTF is wrong with you people?
If you tell your friend you got the white marble, and they see a white marble too, they know someone has been at their marbles.
So if your encryption key is compromised, you lose your marbles?
You are not a brain: http://books.google.com/books?id=2oV61CeDx-YC
I always thought that using a one time pad could use something like a simplified key. Take a irrational number like Pi, and then use an offset and size (length) for the pad instead of the whole key.
The critical part of a one-time pad is that each bit of the key is truly random: there is one bit of entropy for each bit in the key. Anything less amounts to reusing bits from the key, so it's no longer "one-time". What you've described is essentially a form of pseudo-random number generator, with the offset into Pi as the seed. A PRNG can form the core of a symmetric encryption algorithm—just XOR the pseudo-random bit-stream with the message—but it isn't a one-time pad because the entropy of the PRNG output is limited by the entropy of the seed.
For example, the offset in your example would only require a brute-force search through an approximately 56-bit key space (the first 2^56 digits of Pi). If the message is much longer than 56 bits, and not random, then a brute-force search is likely to be able to distinguish the correctly decrypted plaintext from random noise. If there are patterns in the PRNG output it may be possible to take shortcuts and reduce the search time. A true one-time pad has a key for every possible combination of plaintext and ciphertext, so a brute-force search cannot tell you which key was used, or which message was actually sent, and there are no patterns for cryptoanalysis to take advantage of.
"The state is that great fiction by which everyone tries to live at the expense of everyone else." - Bastiat
Because Quantum Entanglement is not in the bible.
"...and god said, 'Let there be photons. And there were photons.'"
“In the beginning, there was nothing. Then God said, 'Let there be light'... and there was still nothing but, you could see it." :: Groucho Marx
Signatures are a waste of bandwi (buffering...)