[HN Gopher] Unforgeable Quantum Tokens Delivered over Fiber Network
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Unforgeable Quantum Tokens Delivered over Fiber Network
Author : pseudolus
Score : 63 points
Date : 2024-12-22 11:53 UTC (4 days ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| londons_explore wrote:
| I am worried about the future of quantum tokens...
|
| Whilst theoretically they are secure, I worry about potential
| huge side-channels allowing leaking of the key...
|
| All it takes is a few extra photons emitted at some harmonic
| frequency for the key to be leaked...
|
| I would much prefer dumb hardware and clever digital software,
| because at least software is much easier to secure against side
| channels, and much easier to audit.
| tucnak wrote:
| Hybrids?
| Strilanc wrote:
| In principle quantum communication has no side channels because
| side channels act like measurements, and measurements make it
| not a functioning quantum channel in the first place. So you
| need to have already solved side channel issues for basic
| function.
|
| That said, wherever you convert the quantum data into classical
| data there will be potential side channels. For example, there
| have been attacks based on using a laser down the communication
| line to track the orientation of the measurement device at the
| receiver.
|
| In general, the more you can do while the data stays quantum
| the better. For example, if you transduce the photon into a
| qubit inside a quantum computer, then the measurement can be
| hidden away inside the computer, instead of exposed to the
| communication line. And the measurement basis can be chosen
| after transmission arrival, instead of before.
| robryk wrote:
| The larger issue for most quantum key exchange setups is the
| transition from classical to quantum: you want not to
| accidentally generate two unentangled photons in the same
| secret polarization.
| UltraSane wrote:
| Isn't the entire security of Quantum Communication predicated
| on its complete lack of side-channels due to the fact that
| measuring quantum systems collapses their wave function?
| TachyonicBytes wrote:
| Yes, in theory. In practice, photon generators won't behave
| perfectly. There are lots of possible attacks, like photon
| splitting [1].
|
| [1] https://onlinelibrary.wiley.com/doi/full/10.1002/qute.202
| 300...
| gus_massa wrote:
| Once you put error correction, doenn't you lose all the
| nice properties of the non cloning theorem? If the protocol
| tolerates 30% of errors, doesn't it tolerate 30% of MITM?
| (60%??)
| TachyonicBytes wrote:
| You don't need error correction for some crypto
| primitives. There are QKD networks deployed that don't
| have that kind of error correction, as far as I know.
| fouric wrote:
| No-cloning theorem applies to logical qubits too! That
| "30% of errors" doesn't allow you to read out the logical
| state. Information is physical.
| TachyonicBytes wrote:
| With quantum tokens, law enforcement have to crack your
| physical devices, so they at least have to good-old-fashion bug
| your devices. With classical schemes, they can intercept on the
| way.
|
| I wouldn't say that current side-channels, most certainly
| enabled by hardware, not software, are easier to audit.
| Vecr wrote:
| I don't think that's true. If you're paranoid you can build a
| very simple and easy to audit device that lets packets
| through exactly every x microseconds, with a short buffer to
| prevent timing via dropouts.
|
| Works fine for digital, doesn't work for quantum stuff.
| foolfoolz wrote:
| "lawful intercept" can be mandated to be built into anything
| thrw42A8N wrote:
| Yes, but it's much easier to see it in hardware than in
| software.
| joshmarinacci wrote:
| Security is never about absolutes. It's about relative costs vs
| the attacker. It seems like this system adds a strong enough
| layer of security over the transport that the attacker would
| switch to going after the endpoints instead.
| amluto wrote:
| Does this have anything resembling details? The press release is
| here:
|
| https://www.nec.com/en/press/202411/global_20241118_01.html
|
| And it has goodies like:
|
| > Token: A digital certificate indicating certain rights and
| values, such as digital assets, user information, and access
| rights.
|
| That is not much detail.
|
| > Quantum key distribution (QKD) systems use quantum mechanics to
| share random secret keys between two communicating parties in
| order to guarantee secure communication, and then encrypt and
| decrypt information based on those keys. (Patented (as of
| November 18, 2024))
|
| This sounds like rather old technology. What exactly is novel
| here?
|
| In any case, the article's drawing makes it look like the
| customer's "token" is some classical information. This cannot
| work.
| yowayb wrote:
| How does a quantum state travel through fiber? Does it simply
| maintain state naturally during the journey?
| amluto wrote:
| Light is remarkably good at keeping its polarization state
| intact for long distances through single mode fiber. At least
| historically, the main issues with doing quantum computation
| with light is that's it's hard to store light and hard to get
| one photon to interact with another one in a controlled manner.
|
| (Polarization of a photon is a two-state quantum system,
| otherwise known as a qubit.)
| xyzzy123 wrote:
| Is there any projected practical use for QKD apart from being a
| jobs program for researchers?
|
| (This is a thing I am fine with, research is research and it
| doesn't necessarily need a near-term practical outcome, but why
| is it "sold" to the public as though there is some useful
| capability coming just around the corner?).
|
| Who would use dedicated fiber to get secrets between point A and
| point B? Am I just insufficiently imaginative?
|
| Whenever I read these headlines I am reminded of how much
| biological research needs to have a "could one day cure cancer"
| to give funders and journalists a hook.
| ano-ther wrote:
| Large companies and governments go to some lengths to protect
| their internal communications between their sites.
|
| Cloud providers also have some dedicated fiber between their
| data centers.
| xyzzy123 wrote:
| Right but what are you going to do with these keys you
| exchange? Load them into networked traditional computers?
|
| If the computers are secure they can presumably do key
| agreement perfectly well and if they are not then I don't see
| how the QKD helps.
|
| Security is nuanced and thinking in binaries is often a
| mistake - but I don't see how QKD meaningfully changes
| anyone's threat model in any plausible scenario.
| conartist6 wrote:
| I keep thinking the headline says "unforgivable tokens"
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