Topic: Quantum computers: possible menace to Bitcoin? - page 2. (Read 3040 times)

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?

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.

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.

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.

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.

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

Eth.

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.

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?

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.

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.

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.

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

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.

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.

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

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

Simple answer.

No

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

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.