Why does this matter?<p>One of the most notorious threats to blockchain-powered networks is allowing a malicious actor to obtain control over more than half of the network's computing resources. This situation is commonly referred to as the elusive "fifty-one percent attack." It is difficult, but not impossible to pull off —<a href="http://motherboard.vice.com/blog/bitcoins-fatal-flaw-was-nearly-exposed" rel="nofollow">http://motherboard.vice.com/blog/bitcoins-fatal-flaw-was-nea...</a> — the aggregation of this kind of hashing power. And it looks like we've nearly made it there again, but there is a difference between a pool getting > 50% of resources, and an "attack."<p>A successful attack using this method would allow the attacker to exclude, or "orphan" any new blocks from the valid chain causing all newly-minted coins go to the attacker. He may also execute a "double-spend" and reverse any of his own transactions during the window of time that his sham blockchain is considered authoritative by the network.<p>A successful 51% attack on Feathercoin — <a href="http://www.coindesk.com/feathercoin-hit-by-massive-attack/" rel="nofollow">http://www.coindesk.com/feathercoin-hit-by-massive-attack/</a> — was stopped in its tracks by the network's natural uptick in difficulty in response to an increase in network hash rate. The Feathercoin attacker was likely executing a price pump in parallel to compromising the network, which caused coin-switching pools to mine feathercoin and increase the difficulty to a level that stopped the attack.
Interesting data point, thanks!
If all the compute power that together forms the GHash pool were controlled by a single entity, this would be an issue. Thankfully that's not the case.
What % of HN knows what this means? Maybe this should be a blog post instead and explain what a "mining pool" is. Or what is the significance of one pool taking over the market.
as a long time proponent of BTC, this is the first time I'm truly worried. Not that I think GH will do anything 'dodgy', just that it's <i>actually happened</i> and that's not a good thing at all.<p>GH just did a great job, I think when other competitors step up and provide as good a service - this will become a distant memory of the past - a blip on the radar (I hope).. There'll be a handful of decent pools, thereby never letting this happen again. (I hope again)