Satoshi wrote this in the original Bitcoin paper, which logic I think still holds today:<p><pre><code> If a greedy attacker is able to assemble more CPU power than
all the honest nodes, he would have to choose between using it
to defraud people by stealing back his payments, or using it to generate
new coins. He ought to find it more profitable to play by the rules, such
rules that favour him with more new coins than everyone else combined, than
to undermine the system and the validity of his own wealth.</code></pre>
These discussions seem fairly relevant now:<p><a href="https://bitcointalk.org/index.php?topic=393815.0" rel="nofollow">https://bitcointalk.org/index.php?topic=393815.0</a><p><a href="https://bitcointalk.org/index.php?topic=399313.0" rel="nofollow">https://bitcointalk.org/index.php?topic=399313.0</a><p>"...if every bank vault in the world had a vulnerability that you (and only you) could exploit, possibly without detection (or at least with a degree of deniability)... what would you do?"<p>Most people wouldn't immediately do the (irrational) thing and abuse that power on a large scale because obviously, the global instability/problems would outweigh the rewards.<p>"Sooner or later, if given the opportunity to take unfair advantage of the system day after day, month after month, I think a lot of otherwise "trustworthy" people/organizations will end up giving in, albeit in subtle ways at first. Most people left to their own devices wouldn't flip a switch (for a reward) to immediately contaminate all of the world's fresh water at once, but if given a million switches each of which contaminates just 1 millionth of the world's fresh water for a substantial reward... I think there'd be some serious switch-flipping going on."<p>The problem with Bitcoin (as described in the original Bitcoin paper) is that Satoshi apparently didn't account for the very real likelihood of pools gaining substantial amounts of power.<p>"If a greedy attacker is able to assemble more CPU power than all the honest nodes..." sounds like a very remote possibility in the context of a world where every miner operates independently, and if pools didn't exist, it probably would be very unlikely. If every miner truly controlled his or her own mining power, I doubt we'd ever run into this problem.
GHash.IO hasn't 51% of total network power anymore<p><a href="https://blockchain.info/pools?timespan=24hrs" rel="nofollow">https://blockchain.info/pools?timespan=24hrs</a>
>There's no evidence the anonymous operators of GHash exercised any of those abilities.<p>Which means it didn't happen. It would be blatantly obvious to watch whenever GHash was mining on the 'wrong' chain to try to make it win. Even if GHash had 80% of the mining power, about one in 25 blocks would see non-GHash miners win twice in a row and unarguably expose this behavior as GHash ignored them.
So what's an individual miner's incentive here to continue mining with a pool that has 51%? If he wants more security in his own mined bitcoins, then surely he has an incentive to switch to another pool?<p>Why is GHash so popular to miners?
Well, for the sake of theory, it's a good thing to think about what the most powerful person in the bitcoin ecosystem could do bad.<p>But please, don't stop here. What the most powerful political leader in your country could do bad ? What the most powerful economical leader in your country could do bad ?<p>"Power" as a concept is something that would need deeper inspection by everyone, and should probably be dissolved as much as possible (that's the point of democracy). If 51% attack scares you, push your reasoning to its ultimate point.
"So-called 51 per centers, for instance, have the ability to spend the same coins twice, reject competing miners' transactions, or extort higher fees from people with large holdings."<p>Woah, can someone please explain why this is?
The thing that surprises me the most is that people were seemingly ok with a player having any large percentage of the network power.<p>The new development seems to be that one player is <i>verifiably</i> controlling 51% of the market. This doesn't mean that two pools who each had 30% couldn't have colluded outside of the network to control it beforehand. I've seen people trying to persuade people not to join the most popular pool but this seems like a more fundamental problem.
Distributed trust systems <i>ought</i> to work because we love the idea, but there is always the chance we shall find that anonymity is not such a good thing for trust.<p>I see no particular reason why bitcoin addresses should remain anonymous in the future, making the impact of this power less, but still a fix to the protocol or a lot more miners will be preferable.<p>I would love to know if this is because the GHash pool has grown (through presumably investing 2012/13-bitcoin profits into hardware) or if it's because others stopped hashing.
Is this really true?<p>So basically any government or any wealthy individual (or maybe even anyone with a botnet) could easily muster enough computing power to destroy Bitcoin?<p>I thought by this point the amount of computing power required to do that was supposed to be ungodly...
It's worth noting that for much of yesterday the parent of Ghash, cex.io, was DDoS'ed. Is this a good thing? Maybe it makes Bitcoin seem more self-policing, or maybe it makes it the currency of scary hackers.
Discussed at length recently: <a href="https://news.ycombinator.com/item?id=7890215" rel="nofollow">https://news.ycombinator.com/item?id=7890215</a>. Unless the present article adds something of substance, I think we have to call it a dupe.<p>Edit: so many people are upvoting this that we'll unbury it.