A Quantum Computing-Dominated World is Coming... (truncated)

[harrymmmm]

QC has limitations.

solving binary logic problems QC doesnt handle well.. expect a 2x 'efficiency' rate
so things like SHA.. dont expect much efficiency of being brute forced by a QC system.

but things like ECDSA that can have deeper efficiency of being brute forced by a QC system.25-256x efficiency.

the thing is though. the cycle rate of a QC CPU compared to a binary based CPU right now has not much difference. so its going to take a while for something desktop PC size to outperform a PC.

QC computers has along time before its truly scaled to compete.

Domination of the blockchain occurs as soon as the first QC with enough qbits is available (anywhere!).
You don't need to wait until they are 'scaled to compete'.
'Enough qbits' means enough to do the hashes and the ecc in reasonable time, of course.

[harrymmmm]

A Quantum Computing-Dominated World Is Coming In Less Than 10 Years, Says CEO Of Acronis

http://www.forbes.com/sites/nanhiein/2016/08/15/a-quantum-computing-dominated-world-is-coming-in-less-than-10-years-says-ceo-of-acronis/amp/

An interesting article on quantum computing, claiming that developments are coming quickly in this area. My understanding is that while bitcoin is not wholly broken by the availability of quantum computers, there would be some things that need to be addressed. I hate to distract from transaction capacity improvements, but does this need to start moving up on someone's to-do list?

Yeah this has been asked before, and the 1st reaction has to be this.  If QC goes main stream, bitcoin security is going to be the least of your worries,  every single encryption method we have will be open for business. 

I think it's important to understand that going 'mainstream' is entirely irrelevant to the discussion concerning 'domination'.
Once there exists a few (maybe just one) QC with enough qbits, the domination occurs. The financial incentives will be irresistable.

[harrymmmm]

Are quantum computers even a reality? Seems like a lot of talk and NO actual demonstration.

Wouldn't be surprised if Quantum Mechanics is just a theory that people started accepting as truth. Probably never going to exist.

Look up the 'quantum mechanic' Seth Lloyd. He demonstrates quantum computing every day in his lab.
FYI, he predicts QC with 50-5000 qbits available within 5-10 years.

[harrymmmm]

An important distinction I don't see anyone mentioning in this thread is between the type of QC used to do stuff like factoring etc, and the type of QC used to do optimization. The latter are call adiabatic (or annealing)  computers.

The article mentioned in OP is concerned with annealers only, afaics. These are the d-wave thingies being used at google, etc. Physicists are still uncertain if there exists any quantum computing going on in these things at all.

The QCs we need to watch for security of the bitcoin blockchain are the factoring type. These already exist, actually do QC, and the estimates for the scaling of them seem to indicate maybe 5-10 years for a worrying number of qbits.

[Slark]

If quantum computing will be reality someday - and if this technology will be really good at breaking encryption, codes, algorithms - all kind of mathematical problems.
Then we are not the ones who should worry, whole banking system will be destroyed as they rely on encryption to keep their transactions and databases secure.
We have quantum processors - but they are horrible now, they need special conditions to operate (to be cooled to absolute zero and be free from any electromagnetic interference).

[harrymmmm]

If quantum computing will be reality someday - and if this technology will be really good at breaking encryption, codes, algorithms - all kind of mathematical problems.
Then we are not the ones who should worry, whole banking system will be destroyed as they rely on encryption to keep their transactions and databases secure.

This is certainly true.

We have quantum processors - but they are horrible now, they need special conditions to operate (to be cooled to absolute zero and be free from any electromagnetic interference).

My point was that 'horrible', expensive and shielding requirements don't matter. The disaster occurs as soon as one exists with enough qbits. Presumably it's existence would be kept secret, but we'd know from the open research how close it was - and that by itself would be enough to cause problems.

tl;dr: without implementation of qc resistant systems, the effects will occur at the tip of research - not when we all have a qc on our desk.

[Yutikas_11920]

If quantum computing will be reality someday - and if this technology will be really good at breaking encryption, codes, algorithms - all kind of mathematical problems.
Then we are not the ones who should worry, whole banking system will be destroyed as they rely on encryption to keep their transactions and databases secure.
We have quantum processors - but they are horrible now, they need special conditions to operate (to be cooled to absolute zero and be free from any electromagnetic interference).

All existing systems in quantum then I think is a good thing. But if for now indeed is not something only gives us an advantage, because in quantum systems have not been effective enough in carrying out all of the existing systems in the world. But I think there is a possibility of future quantum will be a good place to do or change all the existing system because I was looking at the quantum has good potential

[odolvlobo]

... It might more so make PoW more efficient, using less power but make the cryptography part more robust. ...

A common misconception is that if PoW is more energy efficient, then Bitcoin will use less energy.

The reality is that the cost of PoW depends on the value of the block reward. So, if the cost of PoW goes down because of the increased energy efficiency, then economic incentives will cause mining to increase until the cost of the energy returns to the value of the block reward.

The way to reduce the amount of energy used for PoW then is to increase the cost of the energy or to reduce the block reward.

[niagrabill]

If quantum computing will be reality someday - and if this technology will be really good at breaking encryption, codes, algorithms - all kind of mathematical problems.
Then we are not the ones who should worry, whole banking system will be destroyed as they rely on encryption to keep their transactions and databases secure.

This is certainly true.

We have quantum processors - but they are horrible now, they need special conditions to operate (to be cooled to absolute zero and be free from any electromagnetic interference).

My point was that 'horrible', expensive and shielding requirements don't matter. The disaster occurs as soon as one exists with enough qbits. Presumably it's existence would be kept secret, but we'd know from the open research how close it was - and that by itself would be enough to cause problems.

tl;dr: without implementation of qc resistant systems, the effects will occur at the tip of research - not when we all have a qc on our desk.

Bitcoins will begin to disappear all of a sudden and it will be a big mystery. Thats how we will know its quantum computing. The price of bitcoin could crash if we are not prepared.

[Senor.Bla]

it is still the same old story. qc will come eventually and it will change a lot. but bitcoin should not be effected since qc are very specialized in their abilities. bitcoin will have enough time to adjust and most important there are much more higher value targets then bitcoin.

[kryptqnick]

I have seen the news about 2 versions of quantum computer already being created. A lot of people fear this will be the end of btc, because it will be solved. That is not true, however. Even if a quantum computer is 100 000 timess better than our computers usually are, it would take billions of billions of years to break the btc code and stuff. So, my guess is btc can experience the time of price going down but only because of panic, not of the real threat.

[karawantbtc]

I have seen the news about 2 versions of quantum computer already being created. A lot of people fear this will be the end of btc, because it will be solved. That is not true, however. Even if a quantum computer is 100 000 timess better than our computers usually are, it would take billions of billions of years to break the btc code and stuff. So, my guess is btc can experience the time of price going down but only because of panic, not of the real threat.

I read it could calculate a private key in 5 to 10 minutes. This is something to be concerned about.