Topic: Will Bitcoin Bennefit From "Blind Quantum Computing" ? (Read 2184 times)

Unfortunately we can't answer that question yet.  People often drastically overstate the theoretical power of quantum computers. Since the actual power of quantum computers is currently zero (they don't exist), the actual threat is zero and it's hard to reason about how big the ones that might it exist may be because we don't know how to build them.

That said— A very large and fast true quantum computer of a scale which may turn out to not be physically possible could create problems for our ECDSA signatures.

The design of Bitcoin minimizes the exposure there:  If you use bitcoin addresses only once (as is intended for privacy reasons) then your ECDSA public key is only exposed right when you spend, which is just minutes before an ECDSA attack would no longer be effective— so an attacker wouldn't just have to be able to compromise ECDSA they'd have to do it fast.  It's likely that once ECDSA attacks became feasible they would be slow for a long time.

(E.g. even though RSA-512 is crackable (enough so that crazy over computing powered people like me have done it at home) Bitcoin would not be fatally insecure right now if we used RSA-512)

Secondly, our scripting system allows for some kinds of backwards compatible changes. If QC ECDSA attacks started becoming threatening looking we could extend Bitcoin with a resistant signature algorithm (like lamport) and create transactions which require both ECC and Lamport keys. Old nodes would validate only the ECC key and ignore the lamport, new nodes would validate both. 

(The hash functions in bitcoin are probably secure— at least to QC specific threats— QC only provides a sqrt(n) for black box non-linear inversion— so a 256 bit hash has the same security under QC that as 128 bit hash has on classical computer, which is sufficient. This does imply that if miners got QC's which did as many operations per second as their classic computing hardware (a crazy assumption but whatever) then the difficulty would square— e.g. we'd go from difficulty 1,000,000 to 1,000,000,000,000)

QBit only needs a Quantum calculator? I guess my question is will Quantum machines of any kind force a new branch of Bitcoin? Perhaps becoming Bitcoin's platinum, as Lightcoin is its silver?

DWave's system, even believing 100% of their claims, is not a "quantum computer" by the definition used by scientists.  It can't be usefully applied to things like cryptographic puzzles because it just doesn't do that kind of computation.  It would be like calling a machine which can _only_ add integers a computer. Yes, it computes things, but it can't compute in the general sense.  Nor is their engineering approach actually applicable to build something which could properly be called a quantum computer.

I think DWave's system is already 128 Qubit: http://www.dwavesys.com/en/dw_homepage.html

DWave has a system like that already and is planning on opening it's usage to developers. Bitcoin is not a general purpose machine, there are already quantum cryptography key distribution systems on the market, like http://www.idquantique.com/, with miniature quantum electronics already in the laboratory:

http://www.extremetech.com/extreme/108573-worlds-first-programmable-quantum-photonic-chip
http://www.examiner.com/la-in-los-angeles/quantum-computers-on-the-horizon-for-ohio-researchers

It might be overly simplistic for me to model the silicon past into the Quantum future but perhaps the overwhelming benefits of Quantum machines will push the industry to continue Moore's law and since they're really good at crypto it might not be such a leap to imagine miniaturized Quantum miners.

I'm no expert (although Quantum Mechanics and Quantum Physics are my hobby) but I'd say Quantum Computers are currently not feasible for anything more than adding 1+1, and the effort required for that is too much to even bother.

how so?  wouldn't it make more sense that these quantum computers will be in massive buildings where any user from around the world can "jack into" it, thats pretty much what the article alluded to.

I'm my opinion Bitcoin will absorb Quantum Computing since cryptography is one of the methods strong hands. With Moore's law quantum miners will become popular and inexpensive earlier than general purpose Quantum machines and will allow for unprecedented transaction volume and security. I vote we change the name at that point to QBit heralding a new age of complete financial autonomy for the common man.

What do you think?  How do you see bitcoin implementing this technology once it evolves/is proven?  Wouldn't this negate the need for traditional miners?
Article: http://www.bbc.co.uk/news/science-environment-16636580