At the present, does any one company have the capabilities to do it?
That kind of attack is always a possibility, right now no one can perform such an attack but as long as bitcoin exists the 51% attack is going to be a very dreadful possibility. 
Topic: Is a 51% attack currently viable? (Read 1390 times)
Sure, it is always possible. Anyone or any organization that controls over half of the hashing power essentially controls Bitcoin. They can re-write transactions, and do whatever they please. And technically it isn't illegal, or it shouldn't be given it is something everyone already knows, an open flaw in the system if you will, and it is free to be exploited.
I'm more terrified about an attack made with 20% or 10% hash rate that would involve empty or half empty blocks.
Even a 10% drop in the network capacity to rely transaction would really spike the fees beyond 800 and maybe 1000 satoshi/b.
And that would be pretty damn bad.
Especially right now as we see hashrate going away and we will have till the next difficulty even slower blocks.
Even a 10% drop in the network capacity to rely transaction would really spike the fees beyond 800 and maybe 1000 satoshi/b.
And that would be pretty damn bad.
Especially right now as we see hashrate going away and we will have till the next difficulty even slower blocks.
So why the developers don't take any measures to mitigate this risk?
Is there any at all?
Is there any at all?
As with anything that has to do with bitcoin, it's an open market which means it will sort itself out(even if this means a 51% attack). Bitcoin is not going away no matter what any amount of miners do(unless they all stop).
Large companies such as Google has enough money to execute 51% attack. So yes, it's viable but it isn't worth the risk of Bitcoin devaluation.
The biggest threat is a world government using its vast resources to go after a cryptocurrency blockchain is it not?
Never going to happen, unless these etherium freaks pull it off.
for Bitcoin, you'll need hardware worth $1,286,506,150.85 (one point two billion) to conduct a 51% attack
you can have a look at https://www.coingecko.com/en for the latest stats (check the Bitcoin row)
you can have a look at https://www.coingecko.com/en for the latest stats (check the Bitcoin row)
According to Gavin Bitcoin Unlimited could be preparing for an attack anytime and of course, you don't need 51% of the hashrate to accomplish it.You only need to make the original chain unworkable
Well back in the day, when GHash.io was threatening to reach 51% ...Gavin said that there were counter measures that could be used to cancel
these attacks. {He never elaborated on what those was} He was Lead developer at the time and we took his word, without questioning what it
was. I think he hoped people would see that a 51% attack was counter productive and that people would leave these pools, if it became a threat.
i looked around to understand better this 51% and how someone with huge hash can do it, but i see that he need first to make a large purchase with his private offline network which hold the 51% of the net, but by doing this large purchase the vendors can caught him and refuse the purchase or large exchange can stop the deposit or withdrawal of a very large sum that can be seen as a double spend
the important thing about 51% attack is that this kind of attack should be performed for profit not just randomly making a fork and orphaning the 49%!
this means you spend a large amount of bitcoin (for example sell 1000BTC in block 40001) and take the fiat then with >51% start building on top of block 40000 instead and with having more hash power try making your new chain the longest chain and spend the 1000BTC again in the new block 40001.
Note: There is no profit in this either.this means you spend a large amount of bitcoin (for example sell 1000BTC in block 40001) and take the fiat then with >51% start building on top of block 40000 instead and with having more hash power try making your new chain the longest chain and spend the 1000BTC again in the new block 40001.
Let me break it down for you:
You get the 1000BTC in fiat after 6+ confirmations. You mine 6+blocks and overtake everyone else, replacing the blocks. You get the reward, and you get more coins. However, merchants would most likely be alerted to this happening immediately and your Bitcoins are essentially useless; the ones you mined and the 1000BTC you double spent. Remember you have to consider about the money you spent to execute the attack.
^That's from my point of view, theres other perspectives to view it from but thats what you described.
the solution is not that complicated either. when you receive a large amount of bitcion (ie 1000BTC) you have to wait for more confirmation. in other words wait until it is deep enough. double spending after block 40002 is harder than after 40001 and 40003 even harder and 40010 even more and eventually it becomes practically impossible.
The problem is that the number of confirmations just makes things harder for those without 51% of hashpower. As long as they have 51% if the hashrate, they have nearly 100% chance of reversing anything after the checkpoint. Of course, no one would do this since its pointless.
At the present, does any one company have the capabilities to do it?
I can't say it is impossible but it will cost so much for any company or person to conduct 51% attack on bitcoin network. Right now bitcoin network is under massive spam transactions attack rather than 51% attack.
According to Gavin Bitcoin Unlimited could be preparing for an attack anytime and of course, you don't need 51% of the hashrate to accomplish it.You only need to make the original chain unworkable
In the case they attempt to get this suicidal then we will just switch PoW. But those are just all scare tactics, they will never resort to that. Sooner or later Buggy Unlimited will end up as irrelevant as XT and Classic. This is just a battle of pressure and sides are threatening each other with things that will not happen (UASF or 51% attack).
Or that's what I want to think, otherwise someone is really nuts or getting actively paid to attack BTC even if it means fatal damage.
At the present, does any one company have the capabilities to do it?
No, but sadly its not only danger. Imagine two companies alliance to do some %U#( to bitcoin. They could have 30% mining power and 20% mining power for example. But there could be 3 companies... with even lower hash rates but overall over 50%.That is worrying a little bit.
But bitcoin is stronger than that.
BTC.TOP Pool Operator Jiang Zhuoer
BTC.TOP is a relatively new Chinese mining pool. Launched in late 2016, the pool currently controls some 5 percent of hash power on the Bitcoin network.
BTC.TOP is operated by Jiang Zhuoer, a former employee at China Mobile in Shanghai. Much like several other small mining pools that have appeared over the past six months, BTC.TOP has been signaling support for Bitcoin Unlimited.
In an interview with Cryptocoins News in March, Zhuoer was the first who explicitly said a 51% attack against the original Bitcoin blockchain, if it were to survive after Bitcoin Unlimited miners split off, is on the table.
“We have prepared $100 million USD to kill the small fork of CoreCoin, no matter what [proof-of-work] algorithm, sha256 or scrypt or X11 or any other GPU algorithm,” he said, of course referring to the continuation of the current Bitcoin protocol as “CoreCoin.”
The different hash algorithms mentioned by Zhuoer refer to a potential proof-of-work algorithm change Bitcoin users could deploy if the chain is attacked; a “nuclear” defense some Bitcoin Core developers have suggested may be proposed in such a scenario. (Whether this should still be considered “Bitcoin” or yet another spinoff altcoin is subject to different debate.)
“Show me your money,” Zhuoer added. “We very much welcome a CoreCoin change to [proof of stake].”
(If no proof-of-work algorithm succeeds in deterring the attack, a proof-of-stake consensus algorithm — where coin holders rather than miners vote on the longest chain — may be an alternative solution. But since this is unproven and perhaps insecure, this seems highly unlikely
If it was noticeably getting close, people would probably avoid their services and prevent it like they did with ghash.io.
i don't remember anybody "preventing" anything with GHash.IO!
In reality, the possibility of them executing a 51% attack is near to zero. They had datacenters, ASIC and an exchange. If they execute an attack, it would just be like committing suicide.
51% attack is always possible. The top mining pools can easily collaborate together and launch the attack. If you are referring to one owning the resources himself, its a no. It is way too expensive to accumulate that much hashrate.
There is currently no economic incentives to executing such an attack.
the important thing about 51% attack is that this kind of attack should be performed for profit not just randomly making a fork and orphaning the 49%!
this means you spend a large amount of bitcoin (for example sell 1000BTC in block 40001) and take the fiat then with >51% start building on top of block 40000 instead and with having more hash power try making your new chain the longest chain and spend the 1000BTC again in the new block 40001.
the solution is not that complicated either. when you receive a large amount of bitcion (ie 1000BTC) you have to wait for more confirmation. in other words wait until it is deep enough. double spending after block 40002 is harder than after 40001 and 40003 even harder and 40010 even more and eventually it becomes practically impossible.
I don't think a company can really attack bitcoin that high, and I really think this is not viable right now and because of certain miners that are out of the pool bitmain is just 20% over that control, we will not see some bitcoin invasion action for now because the security of bitcoin is really impenetrable right now that is why we are safe!
If it was noticeably getting close, people would probably avoid their services and prevent it like they did with ghash.io.
i don't remember anybody "preventing" anything with GHash.IO!
In reality, the possibility of them executing a 51% attack is near to zero. They had datacenters, ASIC and an exchange. If they execute an attack, it would just be like committing suicide.
51% attack is always possible. The top mining pools can easily collaborate together and launch the attack. If you are referring to one owning the resources himself, its a no. It is way too expensive to accumulate that much hashrate.
There is currently no economic incentives to executing such an attack.
If it was noticeably getting close, people would probably avoid their services and prevent it like they did with ghash.io.
i don't remember anybody "preventing" anything with GHash.IO!
if my memory serves it was like this, GHash.io had more than 51% hashrate (
then since they were a mining pool apart from having GHS themselves, some miners moved to other pools and the percentage came down.
edit: there you go, from 2014:
and just FYI, nothing bad ever happened. someone having high hash power doesn't mean they are going to double spend.
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