Quantum Cryptography Now Fast Enough For Video 69
cremeglace sends in news of a major advance in the speed of quantum key distribution. "Researchers at the Cambridge Lab of Toshiba Research Europe have solved the problem of transferring highly sensitive data at high speed across a long distance network. The team were able to demonstrate the continuous operation of quantum key distribution (QKD) — a system that allows the communicating users to detect if a third party is trying to eavesdrop on the data communication — at a speed greater than one megabit/sec over a 50 km fibre optic network, thanks to the use of a light detector for high bit rates and a feedback system which maintains the high bit rates during data transfer. ... The faster one megabit/sec data handling will allow the one-time pad to be used for the encryption of video — a vast step forward over the current ability to only encrypt voice data."
And if there's a man in the middle? (Score:3, Insightful)
So if someone is eavesdropping, I won't be able to watch the video?
Re:And if there's a man in the middle? (Score:5, Insightful)
MPAA dream? (Score:3, Insightful)
I wonder if some interesting contributors could be noticed in founding sources...
sigh, the "quantum" buzzword (Score:3, Insightful)
So, do we still need the magic secondary channel which everyone doing transfers over this "theoretically perfect" channel conveniently forgets?
Re:sigh, the "quantum" buzzword (Score:4, Insightful)
The secondary classical channel verifies the integrity of the quantum channel. How are we assured of the integrity of the classical channel? We're back to the same weak point we had in the first place: the integrity of a classical channel. If that's insecure, then there's no hope of being assured that both quantum and classical channels aren't being created by Eve. Unless I'm missing something, but it hasn't been pointed out to me yet.
Your one-time pad distribution problem comes down to the same thing. Every practical implementation of quantum transmission lines relies on a classical transmission line in some way.
Re:sigh, the "quantum" buzzword (Score:5, Insightful)
(1) Neither of your scenarios covers the case where both the quantum and the secondary channel are created by Eve, not just the secondary channel;
(2) How is the relationship between quantum and classical channels informed to Bob by Alice?
(3) If your solution is to transport a one time pad at some earlier point "by some other means", then you're copping out twice over, as now we need another classical channel to transmit one time pads long enough for message exchanges.
Encryption will only do so much (Score:5, Insightful)
(1) Neither of your scenarios covers the case where both the quantum and the secondary channel are created by Eve, not just the secondary channel;
In other news, no encryption system, even some hypothetical mathematically perfect cypher, will guarantee that Bob is not actually Eve with a pair of socks stuffed down her jeans. No encryption system will tell Alice that Bob really is Bob. No encryption system will warn Alice that Bob is shagging Eve and talks in his sleep. No encryption system will warn you that Eve has tampered with your hardware. No encryption system will magically turn Alice and Bob into experienced cryptographers who will spot tampering.
Of course, you can use encryption to set up something like a trust network to validate identity, but at some point in the chain a human being has to positively identify Bob and Alice and hand them their "credentials". Likewise, no encryption system can be secure against arbitrarily sophisticated hardware/software tampering.
When you have a sexy cypher which the math says is uncrackable its easy to forget that the math depends on a whole raft of assumptions and assertions.
Re:Encryption will only do so much (Score:3, Insightful)
Very well said.
The main confusion that could so easily be avoided, is that when using the ABC names of Alice Bob and Carl (+ Dave and Eve if needed), people speak as if these are people, when they should out right and explicitly state those are the names of the key pairs.
Once you realize the encryption only exists between named key-pairs, there shouldn't be confusion as to whom can send/read what.
If I use my Bob key pair to encrypt a message for Alice, I can actually be pretty sure that only the Alice key pair can read my message.
Now, as to what person has the Alice key pair, if it is indeed the person Alice or not, is not something public key cryptology even addresses.
Once that little incorrect link is removed (A key-pair is not a person), the rest falls into place.