Bitcoin Forum

Imagine somebody buys one of these (http://www.dwavesys.com/quantum-computing) and turn it on mining.

This would bring the next increase in difficulty to hell, so much that the cost for mining would disrupt any income for anybody.
Nobody would mine anymore, apart maybe the owner of the quantum cpu.
That brings us straight into the 51% danger, right?

A quantum cpu may not be economically cunning AT THE MOMENT, but when the Bitcoin value will grow, the cost of a quantum cpu could be well worth the cost.
Or imagine a central bank that wants to destroy Bitcoin: just buy one of these and fuck up everything in one week.

This has been addressed a number of times.

https://bitcointalk.org/index.php?topic=133425.0

As I understand, if the threat ever emerged, the devs would have enough time to hard-fork to SHA512d as the hashing algo in a worst-case scenario.  Hashing itself isn't effected, but the infrastructure supporting the network could be.  The quantum CPU would also have to have enough scalable RAM to perform the computations necessary to bruteforce the entire network, the tech for which is 50+ years away.  Plus the cost would become insurmountable, especially once mining chips reach the 10nm architectures and beyond, which is expected to happen in the next decade.

So no, not really a threat AKAIK.

What a waste of words.

It took less than 10 seconds with a Google search engine to turn up the following:



Did you put any effort at all into figuring out if your FUD had any merit before you came running to the forum to declare a "menace" that has already been discussed dozens of times over the past 5 years?

Doh I didn't expect somebody would have thinked of this already, sorry  :-X

But I can't understand one thing: you hard fork to SHA512 and difficulty increases for everybody, where's the solution?

Thanks for the link, I'll read that.

Cool down, kid.
I didn't declare anything, you may have missed the question mark in the very title.
You want to say I don't know stuff: that's right.
You want to say I didn't search: that's right too. I wrote I didn't imagine somebody thought about this already. My fault.
But forums are here to spread info, also.
Now if you are annoyed of spreading info, just don't do it.

Anyway, by the time quantum computers are available for the public, all bitcoins have already been mined...

Do you think quantum's will be ready for the next 5-15 years? no way...

Eth.

The same questions being asked over and over by newbies.
No, relax, nothing will kill bitcoin.

The next question would be. How would quantum computers do if they can make it next year(Economically)? Spend million bucks for a handful of BTC? And then what? One could gain BTC efficiently by buying it. Using Quantum Computers doesn't seem logical.

As I wrote, you don't need to have them available to the public: a big institution could want use it to destroy the Bitcoin system, and we know banks aren't waiting for anything else.
And yes I think quantum cpu will be available to big companies in the next 10 years.

Imagine that on October of 2015 1 BTC will be 100000 $.
You can't know it.

Simple answer.

No

Quantum computers are still ideas, it will take decades to become true.

we need a more comprehensive FAQ to avoid repeating same educational points.

Even when they are available  they will be prohibitively expensive for quite a while. If they would ever be a threat the developers would have ample time to address it.

Just to play the role of devils advocate, what if something were to happen like the professor that was banned from using the supercomputers? One could simply "borrow" a quantum computer to mine bitcoin for some temporary period without paying anything.

As was pointed out above quantum computing would not be a very efficient way to hash.

I can't understand why you say this.
For the little I know, quantum computing should empower cpu by 1000 of times.
Maybe we still don't know how to code with qubits?

But apart this, I can't see how a qubit, that can be in many superstates at once, can't be a much more efficient way to hash away numbers.
It should be super efficient exactly in that, because it would make many more tests per second than cpu with 0-1 bits.

Probably because hashing is a very straightforward, mostly arithmetic process.
Quantum computing functionality needs to be combined with quantum algorithms
in order to enjoy greater speed than classical computing.

At this point, and unless something amazing happens, I still think that quantum computers are way far away to affect bitcoin.

In the case that in 10 years, any government or high power institution could put their hands in a superquantum computer, they could destabilize a bit the economy perhaps... but at that point the remaining of un-mined bitcoins will not represent the same risk as if it would happen right now.

My .00000002 BTCs

Eth.

OK so let it be about quantum computers.

Let's assume that a fellowship of banks want to destroy Bitcoin.
They buy computing power from a couple supercomputers and make, in a single 2 weeks session, jump the difficulty to the stars, so that mining becomes highly unprofitable, so pushing miners away from the business.
They would hold this status until they see most if not all left the mining business, then drop the renting of supercomputing power.

Is this a possible scenario?

No.

Mining is basically hashing, which is not a quantum algorithm.
Quantum computers or supercomputers won't help.
This kind of attack would involve trying to buy ASICS.

Bitcoin price skyrockets due to its limited nature. Miners are rich from past reserves. Bank gives up. Miners earn money from transactions.

Eth.

Banks are much more rich than miners.
Banks can keep up mining without rewards (i.e. losing money) much more than actual miners.
Miners don't earn enough money from transactions at the moment. In the future, when billions of people will use BTC, yes, but now, they don't.

BTC price will skyrocket when mainstream will kick in.
Don't know when this will happen yet.
At the moment only geeks, speculators and anarchists are jumping on the Bitcoin wagon.

Based upon the number and type of questions you're asking, my guess is you haven't done a lot of personal research about Bitcoin.

First, despite what anyone is telling you on this forum, *nobody* here knows what the true state of quantum computing is like.   It's been asserted in this thread that quantum computing is nowhere near the point where we can crack SHA-256 with it.  This is almost assuredly true given that there is no known instance of quantum computers wreaking utter havoc on everything.  I'm pretty certain that if such an advanced computer existed, someone somewhere would have blown something up with it a long time ago.  But, when you go off talking about supercomputers, this is different than a quantum computer.  Currently, even an entire cluster of supercomputers wouldn't push the difficulty very high -- the network is currently *far* more powerful.

Second, if that's the best plan you think a bank could come up with, let me tell you something -- it sucks and is somewhat laughable.   As I just alluded to, supercomputers would definitely not be the way to go here.    Forcing some type of scenario where the profitability of mining drops to zero or becomes negative is somewhat pointless if all you're trying to do is stop people from mining.  Mining will always move towards an equilibrium between cost and benefits -- if difficulty increases to a point that threatens profitability, miners will drop out, and when the difficulty goes back down after they drop out, you'll see miners jumping back on board.

Third, even if you did have a quantum computer that was powerful enough to crack SHA-256, then believe me when I say there are a *lot* more profitable targets than Bitcoin.  

Fourth, what would it matter if they "drop the rent of supercomputing power?"   Aside from the fact that I mentioned earlier that supercomputers are little wimps compared to the Bitcoin network, how would making hashing power more affordable threaten the network?  

Currently, as I see it, the easiest way for a large entity to kill Bitcoin would simply be to buy enough ASICs to gain a majority share of the network hashrate so they can control it at will (or just buy and sell a large, random number of BTC every day to make it intolerably volatile for an indefinite period, but let's forget about that one for now).  A few billion dollars ought to be enough.  But then the question comes -- "WHY?"

Why spend a few billion (which, even for a bank, is a sizable amount of money) to kill a market that's only worth a few billion in the first place?  All this likely means is that one bank is now out a few billion dollars and are thus economically weaker compared to their competitors (i.e. other banks) who never spent even a penny.  Is a bank really going to sacrifice market share to its competitors based upon some *potential* treat?  Now, if the market cap of Bitcoin was tens or hundreds of billion dollars, this would imply that the network hashrate is many times greater, and now it becomes difficult for even a bank to scrounge up enough money to purchase the hardware required to gain a majority share of the network.

TL;DR:  Bitcoin has natural incentives built into it's core model that dissuade people from attacking it.

ASICs can only do one specific task - that is to mine bitcoin or other SHA256 algo coin.

Quantum computers can do a wider range of functions and as a result will be less efficient at mining then ASICs would be.

If quantum computers were actually available (at least to someone) and were effectively able to successfully attack cryptographic algorhitms, there would be a lot more profitable ways to use them; and, if one really wanted to use them against the Bitcoin ecosystem, cracking private keys would be a quite more useful target than mining.

When it comes to menaces, my only realistic concern I can think off is someone (or a group off) extremely rich people (think the Bilderberg Group for instance) decide to fuck up Bitcoin for X reasons, buy an insane army of ASICS and aim them all strategically to go 51%++

What do you think of such sceneareo?

all i can say on this matter is a future bitcoin update will allow both rsa256 addresses and rsa2046 addresses. just like bitcoin protocol allows compressed addresses, etc at the moment.

it would have to be an "allow both" at first, so that way its not a hard fork so that people that want to use old software and stick with 256 can, although they would need to update to pay/be paid in rsa2046 payments

then everyone would move their funds from 256 to 2046. this will then make pruning easier once alot of the old blocks that people have not touched, have moved their funds. making old blocks redundant(spent).

Bitcoin uses ECDSA not RSA.   RSA requires significantly larger key sizes than ECDSA for the same level of security so it probably will never be used for a blockchain based technology.

Yep, or regulate it to death so it won't be mainstream,  or buy and sell large, random amounts frequently for an indefinite period of time to create intolerable volatility.

In case a technological defense wasn't implemented,
the community could decide to fork to a different
proof-of-work algorithm such as SHA-3, and all
that planning and tens of millions of dollars spent
to attack Bitcoin would be for nothing.

Great post, thank you :)

As for the WHY question, in this YOU may have to think a bit better.

For the same reason we think Bitcoin will waste banks, banks will one day understand what's happening and WILL probably take any measure to blast it off.

Besides, bilderberg are an interesting club, rotschild is an extremely rich family... if these organizations decide to take action against something that is mining (!!!) their grounds for billions of dollars, they will be glad to spend billions of dollars to protect their markets.

I think the genie is out of the bottle.  Cryptocurrency is here to stay one way or another.
At some point even the staunchest opponents will have to accept that.

Maybe. I hope so.
But I find it strange that banks are not taking countermeasures to blast it off.
I didn't see any serious attempt to kick Bitcoin off the moon, and this scares me a bit.

The profitable way to use these kinds of technology would be to simply mine altcoins on a multipool, trying to do anything else would likely cost more then it would generate in revenue.

But we are not here to talk on how make them profitable, but if they were a good resource to destroy Bitcoin.

If they were a viable menace to cryptography in general, every secure communication in the world could potentially be compromised, including web sites, digitally-signed emails, and so on. If that stage was to ever be reached, I'd be a lot more worried about credit cards and bank accounts than Bitcoin wallets.

Because you are thinking like a robber, not like a central bank director.

Yeah, but also, I think sometimes people compliate it so much. What about good ol old school bribing? Let's say a super powerful wealthy entity starts a plan to bribe current stakeholders. Say, the Winklevii. They great approached by said super rich entity, and they get told that, if they sell all of their stake to said entity, they will recieve a ridiculous amount of interest as well.
They do this with every single stakeholder.
From an outside POV, if done subtly the price would go low for sure, but Bitcoin has taken a lot of blows already and recovered. What would have changed in this scenareo is that all the big stakes now belong to an institution with evil intentions.

No need for "bribing".  Entities that wish to acquire coins can simply buy them
at or above market price.   If i was super wealthy and wanted a ton of coins,
I would be contacting large miners, not the Winklevii, as well as purchasing
over time from exchanges.

Well I don't necessarily agree with this. There has to be and there will be something that will come along and kill bitcoin. Such as the end of electricity, Armageddon etc. xD

end of electricity/Armageddon will kill all currency, all you have left to rely on is food and a gun/knife. money will be meaningless so people wont care about money in those 2 scenarios, only survival

Good point. I didnt think that far ahead.... Hell I bet you could trade a pound of gold for a 16 oz sirloin if that happens.

Paper money would still potentially have value as people will need something to trade with.

Bitcoin is invulnerable to this kind of things, even if those transformer guys come and try to menace Bitcoin will fail.

But we, Bitcoin holders are not invulnerable, on the contrary, if one of those things comes to appear, god help us with scammers, reivers hackers and evil people who will use that quantum power to f*ck our lives.

What we needed, quantum scammers  >:(

Bitcoin will adapt to quantum computers when they come, this topic is addressed well here: http://www.panture.com/how-quantum-computing-will-affect-bitcoin/

Paper money would still potentially have value as people will need something to trade with.
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if i told you that the electricity had gone and that means no ATM's, no bank systems, no cashier machines. would people care about paper money.. no, because bank notes utility and access has just gone. (watch the TV show 'revolution')

if i told you the world is about to end this week, why would you accept a bank note, after all what can you do with a bank note. id prefer a gun and a car. but i wont have months of working to earn enough bank notes to get a car and gun in a week. so as everyone will be dad next week. ill just break a car window and take it.. that's why its called an apocalypse.. civilization ends!