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Bitcoin’s race to outrun the quantum computer

decrypt.co

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Re: Bitcoin’s race to outrun the quantum computer

#51

Post by londons_explore »

xiphias2 wrote: post #26
rolltiide wrote: post #24

Earlier quoted context omitted.

Its not much harder for bitcoin... The community will just do a blockchain snapshot of balances at an agreed upon block and start a new distributed ledger with quantum resistant encryption Snapshots have been done hundreds of times

It's easy to add a quantum resistant algorithm, but as it's much more expensive to verify and takes more block space, the transaction fees will be much higher. Transitioning is a huge political problem as well.

It'll be politically easy. Nobody wants someone else able to steal their money.

Re: Bitcoin’s race to outrun the quantum computer

#52

Post by beambot »

mlyle wrote: post #45
krastanov wrote: post #39

Earlier quoted context omitted.

We definitely are getting closer. Look at any graph of "qubit lifetime" and you will see how we have orders of magnitude improvements. (a quick google search gives me page 9 of https://hpcuserforum.com/presentations/tuscon2018/QCOverview... ). We still need a couple more orders of magnitude before the qubits are useful, but the signs of exponential progress are unmistakable. I would not take any experiment performing…

So if we extrapolate out the current curve 2 more orders of magnitude, it looks good. Therefore we can conclude it's looking possible? ;)

For historical precedence, see "Moore's Law"

Talking to experts in the field, we're doubling the number of functional qbits (ie accounting for error correcting requirements) about every 12 months right now. Looks like current number is 16-qbits, where many algos get "really interesting" around 1000 qbits (and functional even before that). So 5-6 years until a potential total transformation in computing paradigms. Quantum is in a similar place as deep learning in 2012.

Re: Bitcoin’s race to outrun the quantum computer

#54

Post by sroussey »

bhouston wrote: post #53

Will breaking classic computer public key encryption reveal any secrets that were encoded prior to them being obsolete? Should we be recording encrypted streams and saving them for a few years until we can break them? Is there any value in that?

What do you think the NSA is doing?

The public blockchains make all this more feasible since they have the community keep the data around in original state for them!

So much cheaper than recording SSL/TLS traffic, for example.

Also that is why they would find it important to exfiltrate the data from a company (or government) before it can be re-encrypted with something better.

Re: Bitcoin’s race to outrun the quantum computer

#55

Post by sroussey »

DennisP wrote: post #12
ddtaylor wrote: post #9

It's worth mentioning that Bitcoin addresses aren't exposed on the blockchain as public keys, but hashes of the public keys. If you want to steal the coins you'll need to turn ripemd160(sha256(sha256(publicKey))) into a private key. Good luck.

Yes, but the public key is exposed when you send from that address. If a quantum computer is quick enough, it could get your private key and issue its own transaction, racing you to get into a block.

It doesn't need to be quick if you still have coins at that address.

Re: Bitcoin’s race to outrun the quantum computer

#56

Post by marcus0x62 »

krastanov wrote: post #41
Causality1 wrote: post #13

Earlier quoted context omitted.

We seem to be getting better at using quantum computers for hard math. What I'm curious about is when we'll be able to use them for easy math. How many qubits do we need to run Doom Quantum?

Quantum computers are (conjectured to) outperform classical computers in a very restricted set of problems. These problems happen to be extremely important (e.g. protein folding and some forms of linear algebra), but for tasks that are already efficiently solved by classical computers you probably will never use a quantum computer (maybe in many decades this will change, when it becomes as "trivial" to construct quan…

Or the subset of users who need what a quantum computer can offer add something analogous to a GPU to their general purpose computer.

Re: Bitcoin’s race to outrun the quantum computer

#57

Post by The_rationalist »

krastanov wrote: post #4

Just to be clear, this has barely anything to do with any crypto-currency organization. It is a really regrettable framing for an event that should be of great interest to anyone dealing with cryptography, not just the fairly restricted group of crypto-currentcy enthusiasts. If scalable quantum computers can be built (which seems probable, as we are progressing fast in the number of qubits we can keep together), then…

> which seems probable, as we are progressing fast in the number of qubits we can keep together Probable? Ridiculous:

×there are still no hardware implementation of a single logic gate despite what? 40 years of research? ×stability of qubits are pathetic. ×no software stack (almost) ×Number of qubits are ridiculous and 40 years of research can't even make a consensus on how much qubits are needed for beating a CPU on at least one task. Even if quantum could(I strongly doubt that and quantum speedup has never been shown empirically) reduce complexity on some algorithms, the constant factor has no way to be handled with 50qbits, more like 1000000 qbits at minimum. ×no sign of needed breakthrough in error correcting codes.

I consider quantum speedup to be theoretically flawed, based on an interpretation of quantum mechanics needing "parallel worlds" which necessitate a misunderstanding of causality to make sense.

I consider quantum speedup to be flawed in practice too as order of magnitude of order of magnitude progress is needed and the trend is: no progress or very slow progress.

Thus quantum computing is like a vaporware, which take funds that would be far better allocated at e.g medicine, AGI, or ASICS.

Re: Bitcoin’s race to outrun the quantum computer

#58

Post by sroussey »

rolltiide wrote: post #24
zazagura wrote: post #17

Earlier quoted context omitted.

Not really. Your bank (and the whole web) can easily switch to a quantum resistant encryption algo when time comes. For Bitcoin this is much harder.

Its not much harder for bitcoin... The community will just do a blockchain snapshot of balances at an agreed upon block and start a new distributed ledger with quantum resistant encryption Snapshots have been done hundreds of times

> The community will just do ...

This is the funny thing about decentralized services. They require centralized action. Not saying it is good or bad, but it is... different.

Re: Bitcoin’s race to outrun the quantum computer

#59

Post by semi-extrinsic »

The_rationalist wrote: post #57
krastanov wrote: post #4

Just to be clear, this has barely anything to do with any crypto-currency organization. It is a really regrettable framing for an event that should be of great interest to anyone dealing with cryptography, not just the fairly restricted group of crypto-currentcy enthusiasts. If scalable quantum computers can be built (which seems probable, as we are progressing fast in the number of qubits we can keep together), then…

> which seems probable, as we are progressing fast in the number of qubits we can keep together Probable? Ridiculous: ×there are still no hardware implementation of a single logic gate despite what? 40 years of research? ×stability of qubits are pathetic. ×no software stack (almost) ×Number of qubits are ridiculous and 40 years of research can't even make a consensus on how much qubits are needed for beating a CPU on…

While I agree that QC is far from cracking any encryption today or in the near future; this

> theoretically flawed, based on an interpretation of quantum mechanics needing "parallel worlds"

is patently false. There is nothing in QC that would stop working under the good ole' Copenhagen interpretation.

In fact, if there was even a theoretical possibility that a QC experiment would work only in some QM interpretations, they would no longer be interpretations, but falsifiable hypotheses.

Re: Bitcoin’s race to outrun the quantum computer

#60

Post by sweeneyrod »

nielsole wrote: post #47
sweeneyrod wrote: post #29

Earlier quoted context omitted.

Damn, looks like I should stop using 21 as my PK then.

Not sure what algorithm you use for encryption, but 21 doesn't look like a prime. Maybe run a Miller Rabin test on it? ;)

It's the modulus of my RSA PK, so the product of two large primes rather than a prime itself. Of course, I can't say what the factors are, otherwise anyone could crack it even if they don't have a quantum computer!
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