What does Quantum Computing mean for Bitcoin?

[binspac]

The National Security Center is building a highly fortified $2 Billion highly top secret complex simply named the “Utah Data Center” which will soon be home to the Hydrogen bomb of cybersecurity – A 512 Qubit Quantum Computer — which will revitalize the “total information awareness” program originally envisioned by George Bush in 2003.

Why would they be doing this if D-Wave's quantum computers are no more powerful than a cellphone?

Saying they aren't real quantum computers is just disinformation.

Remember when binary computers took up entire rooms? We're at (or past) that state right now with quantum computers.

[1714171707]

1714171707

[MatthewLM]

What about NTRU? Apparently no quantum based attack has been found and the keys don't have to be as long as other quantum-safe crytosystems.

[punningclan]

It probably also means real arbitrary precision and never ending mining even without fees.

[runeks]

2) A 52 bit hash WILL ALWAYS BE SOLVEABLE in 2^52 operations.  It is mathematically impossible to NOT FIND A SOLUTION in 2^52 operations.  Routinely the bitcoin network takes much longer than 2^52 operations to find a solution.  The reason is the KEYSPACE IS NOT 52 bit.  It is 256 bit AND there just happens to be multiple solutions.

Two messages might produce the same 52 bit hash. There is no guarantee that whichever messages you put into the hash function will not produce the same 52 bit hash. Therefore there is no guarantee that you will find all possible message digests in 2^52 attempts. In fact, with a 52-bit hash function there is a 50% probability that two messages will hash to the same value if you try 2^26 different messages.

Or am I misunderstanding you here D&T?

[paulie_w]

http://www.technologyreview.com/news/429429/the-cia-and-jeff-bezos-bet-on-quantum-computing/

interesting.

[MysteryMiner]

Quantum computers are like space travels to nearby galaxies - it is fun talking about them and researching possibilities, but it will not happen tomorrow or next year. Worrying that Bitcoin or asymmetric cryptography will became useless because of Quantum computers is like being afraid of alien invasion.

[Littleshop]

The National Security Center is building a highly fortified $2 Billion highly top secret complex simply named the “Utah Data Center” which will soon be home to the Hydrogen bomb of cybersecurity – A 512 Qubit Quantum Computer — which will revitalize the “total information awareness” program originally envisioned by George Bush in 2003.

Why would they be doing this if D-Wave's quantum computers are no more powerful than a cellphone?

Saying they aren't real quantum computers is just disinformation.

Remember when binary computers took up entire rooms? We're at (or past) that state right now with quantum computers.

No, because when the binary computer took up an entire room, it was in actuality a binary computer as represented.

Scientists in the field say that the D-wave machine is NOT a quantum computer at all. 

[kwoody]

Quantum computing makes me believe that in some alternate universe, I'm filthy fucking rich smoking blunts and surrounded by bitches all day every day. It also makes me believe that in another alternate universe, I've committed suicide by slitting my throat with a dull edgeless spoon.

Oh right, Bitcoin.
Bitcoin exists, is the global reserve currency, and hasn't been invented yet.
Bitcoin doesn't exist, Satoshi was declared dead upon childbirth, and the Bildeburgs are a homeless poor family of Ethiopians.
Pick one.

[grondilu]

Quantum computing makes me believe that in some alternate universe, I'm filthy fucking rich smoking blunts and surrounded by bitches all day every day. It also makes me believe that in another alternate universe, I've committed suicide by slitting my throat with a dull edgeless spoon.

Reminds me of a physicist joke about Everett's interpretation of QM:

«
- According to Everett, there is a universe in which Sarah Palin is president of the United-States?
- Well you know, it has to be compatible with the laws of physics.
»

[TheBible]

It will mean you still can't buy anything with bitcoin.

[Westy96]

I think this issue will bear down on us sooner than expected. I would be interested to hear thoughts on how the change to the algorithms could be implemented, as surely without an automated solution it would be a huge threat to ask users to manually migrate to a more secure wallet for example. A smooth and seamless update to the network is the answer, but can it be done?

Imagine if one day Satoshi's coins move and we do not have a solution in place.   

[matjas]

Depends if we see a slow integration where every system will be able to migrate and adapt to QC, then there wouldnt be such a problem to switch to QC mining. The real threat is if governments (or some rich corporations) are building it in secret and will have a huge advantage over majority of current systems.