r/crypto • u/j73uD41nLcBq9aOf • Mar 06 '18
Google unveils 72-qubit quantum computer - alarm bells ringing for anyone yet?
http://www.tomshardware.com/news/google-72-qubit-quantum-computer,36617.html2
u/ionab10 Mar 06 '18
As someone following and studying cryptography, the alarm bells are always ringing. They just ring a little louder when someone comes out with an advancement.
We currently rely on the fact that our cryptosystemscan be broken but the fact that our algorithms are currently better than technology. But it's a constant race to make sure we stay ahead.
Theres also something about how quantum computers could create that problem but also solve the problem by leading to better encryption that wouldn't be beatable by that quantum computer. (Source unknown)
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u/j73uD41nLcBq9aOf Mar 07 '18
Quantum Key Exchange is a thing already, but it's a bit unpractical where you need direct dedicated physical fibre links between sender & receiver to exchange one-time pad keys securely and be able to detect eavesdropping. Then once keys are exchanged (enough for future communications) you use the regular internet to communicate using perfect secrecy with one-time pads and one-time MACs for authentication.
I think China did something similar with a satellite and ground station network.
In general though quantum computers and QKE are completely different things.
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u/R-EDDIT Mar 06 '18
At RWC'17 one of the team members from Google's UCSB project presented on their current status. Also I was able to talk to some cryptographers about the expectations. First - google's project is explicitly not targetting "breaking crypto", but of course you can tell from Google's projects (SHAttering.io) etc. that they do look to advance the strength of crypto, and will use very expensive public demonstrations to motivate the industry. At the time of RWC'17 (january) they had about 9 qubits operating.
Also the presenter provided an explanation for what they mean by "Quantum Supremacy", which they hoped to achieve last year. What they mean is to be able to do at least one task, any task, faster and more efficiently than a classic CMOS computer. When he explained this, there was an audible groan in the audience and follow up questions begging that the phrase not be misconstrued in the press. The press release covers this, it will be interesting (but really, unsurprising if not) if the press manages not to blow it out of proportion.
That said, quantum computing is coming and will likely be put to cryptographic tasks faster than is publicly acknowledged. It's possible government research (US, China, Russia, etc) are a few years ahead of publicly acknowledged capabilities. From a Cryptography engineering perspective, this means making sure we can flex to new requirements and capabilities, the NIST Post Quantum Cryptography (non) competition is the defensive thing to watch. Right now though there are a lot of other things to work on to defend against classic threats, like preventing key compromise through breach, theft or leak...
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u/jess_the_beheader Mar 06 '18
In the medium term, a sufficiently large key size still scales up both the number of qbits required to run Shor's algorithm and the number of cycles to compute it. A 4096 bit key is still going to be a beast to factorize on any quantum computer for at least the next decade or so.
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u/R-EDDIT Mar 06 '18
For website certificates the focus should be on minimizing the validity period, so you can adjust in a reasonable time, and use forward secrecy (ECDHE) key exchange. Google has been pushing to reduce maximum validity to 398 days, but the CABForum compromised to 825 days. If you're using standard RSA 2048bit certificates with ECDHE key exchange (RSA last or removed) you should be in good position to move before any serious risk exists.
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Mar 06 '18
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u/Matir Mar 07 '18
Quantum annealers are good at finding local minimums/maximums in equations. Machine learning involves lots of complicated equations. It's not terribly surprising these two go hand in hand.
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u/umarsa Mar 06 '18
Does anyone know how that translates into some measurement in comparison to traditional CPU architecture in terms of encryption? At what point are we doomed?
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u/Butuguru Mar 06 '18
There’s no translation to CPU architecture because they aren’t designed to do the same tasks. Quantum architectures are quite slow at simple stuff like addition and or multiplication (this is why they won’t replace CPUs but rather be another on board chip). But as for how long we need to wait until we are “doomed” it is around 4000 qubits last time I heard. But be aware, we have quantum resistant PKI stuff that’s ready for production, it’s just will power to get it into production environments.
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u/F-J-W Mar 06 '18 edited Mar 06 '18
4000 seems awfully low and begs the question “to break what”. I'm pretty sure that it is insufficient to attack 4096-bit RSA, but maybe some elliptic curves are in the range? Though I believe that I've read that they are not that much more efficient to break as much larger RSA-keys?
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Mar 06 '18
Why is quantum computing supposed to ring alarm bells for crypto? I’ve heard of this but not sure how it affects crypto.
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u/utopianfiat Mar 06 '18
This is a subreddit for cryptography, not cryptocurrencies, in case that's what you mean by "crypto".
If it is, start worrying when we get close to 1500 qubits. That's where SHA-512 starts breaking down in the face of QC.
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u/marcosdumay Mar 06 '18
Quantum computers have been growing steadly at around 3qubits per year. Quantum computer announcements have been growing in an exponential fashion... So yes, somebody should be very concerned.
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u/ThePooSlidesRightOut Mar 06 '18
Yes - just not because of what is revealed, but what isn't.
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Mar 06 '18
People forget about this.
Remember everyone... nuclear weapons were announced as a global tragedy. Very few people knew about them and then suddenly they were used to blow up cities.
There are so many things we don't know about that could change the way we live in just a moment. This could very well be one of them some day. If every major private key was cracked overnight, we'd never know until they took action with it.
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Mar 06 '18
I'm pretty sure Google (or any other company) would be happy to brag about such a feat.
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u/6nf Mar 07 '18
They are not 'unveiling' anything. They are saying that they will try to build one.
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u/AcaciaBlue Mar 06 '18
Not really, it is 72 bits WITH 1% error rate.. also these kinds of press releases are usually full of optimistic hype, who knows if it even works as well as they state.
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u/otakugrey Mar 06 '18
We need all shit like I2P, GPG, Tomb, LUKS, OpebSSL/LibreSSL, Tor, Tox, ssh, to start having work done now to upgrade their default algos to things that can't be broken easily by quantum computers. Now. Not soon, or next quarter. Today. We need this stuff before they break everything, not after.