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Commercial quantum computer leaves PC in the dust

newscientist.com

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Re: Commercial quantum computer leaves PC in the dust

#21

Post by Jach »

swombat wrote: post #4

So, basically, as soon a someone builds one of those optimised for factoring primes, all our encryption methods are finished, as is the Bitcoin economy, right? Assuming the contents of the article are true (which is possible), how long before that happens? A few years? A decade?

Bitcoin is relatively safe; there's Glover's Algorithm [1] which would effectively turn computing sha-256 hashes into computing sha-128 hashes (so I read somewhere) which is a problem, but not an impossible one. The majority of the miners plus core devs can agree to upgrade the protocol to use a different hash algorithm, like scrypt (which Litecoin uses) or something specifically made that's not vulnerable to quantum algorithms. (I don't know if scrypt is.)

This upgrade wouldn't need to happen overnight, either. I bet the first quantum computer that can compute sha-256 hashes at all will do so slower than the latest classical ASICs of the time.

[1] http://en.wikipedia.org/wiki/Grover%27s_algorithm

Re: Commercial quantum computer leaves PC in the dust

#23

Post by rohansingh »

mtgx wrote: post #12
NickM wrote: post #7

Earlier quoted context omitted.

Well, actually not all our encryption methods: there are asymmetric encryption algorithms that provide strong encryption even in the face of quantum computers. Unfortunately, the whole world is using RSA which is vulnerable. I don't know that much about quantum computing, but I believe it may be possible that D-Wave has managed to figure out how to build a useful quantum computer that is nevertheless not general-purp…

When the FBI stops asking for backdoors in Internet services, we'll know they probably don't need them anymore. Then take into account that NSA is already probably 5-10 years ahead of them for any sort of surveillance technology.

A little paperwork to get a backdoor is probably cheaper, faster and easier than using a quantum computer, even if one is available.

Re: Commercial quantum computer leaves PC in the dust

#25

Post by shadowmint »

I wish there was more detail on this comparison, I'm looking forward to the presentation.

That a custom specialized computing device performed better than a desktop computer doesn't sound particularly compelling to me.

Aren't the dwave machines like super computers? Would you expect them to be that much faster than a desktop?

Sounds weird to me.

Re: Commercial quantum computer leaves PC in the dust

#27

Post by shadowmint »

pja wrote: post #16
swombat wrote: post #4

So, basically, as soon a someone builds one of those optimised for factoring primes, all our encryption methods are finished, as is the Bitcoin economy, right? Assuming the contents of the article are true (which is possible), how long before that happens? A few years? A decade?

Pretty much: Quantum Computers (QCs) can factor numbers (Shor's algorithm) and calculate discrete logarithms in polynomial time. I don't know whether there's an algorithm for hash-calculation that will let someone dominate the BitCoin hashing chain with a QC though. On the other hand, no one actually knows whether it's possible to build a quantum computer with enough q-bits that will stay coherent for long enough to…

I actually thought that error correction codes were largely considered to solve the problem of decoherence, at least theoretically.

(aka. http://www.google.com.au/url?sa=t&rct=j&q=&esrc=... or perhaps more easily explained @ http://en.wikipedia.org/wiki/Quantum_error_correction)

Re: Commercial quantum computer leaves PC in the dust

#30

Post by xorbyte »

swombat wrote: post #4

So, basically, as soon a someone builds one of those optimised for factoring primes, all our encryption methods are finished, as is the Bitcoin economy, right? Assuming the contents of the article are true (which is possible), how long before that happens? A few years? A decade?

FWIW, someone on Crypto.SE reached out and received comments from DWave stating that it's not a problem in the foreseeable future.

http://crypto.stackexchange.com/a/439

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