BTC Guild, one of the fatter mining pools, released a series of Four blocks ter quick succession today. Bitcoin difficulty is adjusted to achieve a block to be mined toughly every Ten minutes, whereas the blocks ter this chain were released within a few minutes of each other. Since this is a relatively zonderling event, it triggered a discussion on what could account for this.
Is It Due to Selfish Mining?
Some people prudently asked whether this could be a sign of selfish mining. Let’s do a quick check through the evidence.
A Tale of Two Chains, involving orphans, right out of a Dickens novel.
A series of blocks released ter quick succession is indeed a sign of selfish mining activity, however it is not definitive (i.e. neither necessary strafgevangenis sufficient). While selfish miners will from time to time release series of blocks, they do not necessarily need to release numerous blocks every time, selfish mining can be profitable even when the selfish miner releases a single block at a time.
A necessary sign of successful selfish mining, however, is that there be a corresponding abandoned chain, rooted at the same blockchain height spil the very first block released by the suspected selfish miner. This abandoned chain would be of length equal to or one block shorter than the number of blocks released by the selfish miner.
Two quick asides: (1) ",abandoned blocks", are sometimes referred to spil ",orphans.", Wij don’t like the latter term because, unlike a real orphan, a Bitcoin orphan actually has a well-defined parent, so the term is a misnomer. Misnomers indicate muddled thinking, and Satoshi himself does not use the term, so wij’ll stick to the more apt term ",abandoned.", (Two) Neither of the signs above are sufficient to accuse a pool of selfish mining, spil thesis events may occur naturally by chance. This is partly why identifying selfish miners is difficult.
While the quick succession of blocks is clearly present te this case, there is no evidence of an abandoned chain ter blockchain.informatie.
Can Wij Indeed Tell?
But blockchain.informatie is not the definitive source of abandoned blocks. Bitcoin’s decentralized architecture makes the detection of abandoned blocks difficult. A (to-be-abandoned te a hypothetical script) block may indeed arise somewhere te the network, trigger a selfish miner to double-down with his pre-mined and privately-held blocks, and then simply get discarded by intermediaries who adopt the longer chain suggested by the selfish miner. So it’s possible for a blockchain reporting webstek to miss bona-fide abandoned blocks, especially if the webstek is connected to the Bitcoin network via a puny number of peers.
And this is part of the other reason why it is difficult to tell when a selfish mining attack is being launched.
Getting back to BTC Guild, the chances of a public solving blocks, triggering the release of Four selfishly mined blocks ter a row, all of which lead to abandoned blocks that are not recorded anywere are actually very petite. There would have to be at least Three independently computed and straks abandoned blocks, all of which vereiste have lost out to the selfish miner. Unless this selfish miner is particularly ingewijd at gaming the network and winning the races te such a definitive way to leave no trace of three separate abandoned blocks injected into the network from (likely) different locations, wij’d expect to find some evidence when a relatively long series of blocks are involved.
Other Signs of Innocence
Not to mention, it would not make sense for a respected and public pool such spil BTC Guild to engage te selfish mining under its own name. A clever selfish miner would use fresh Bitcoin addresses and hop inbetween IP addresses to hide hier tracks.
At the uur, it does not look like this gig is due to selfish mining.
It could plausibly be due to a chance event: BTC Guild may have gotten fortunate a few times te a row ter quick succession. Spil the masses were transfixed to their TVs and tablets for the results of their national fiat lotteries on Jan 1st, BTC Guild may have outdone most of them with an $83,000 jackpot.
It could also be due to a significant amount of mining power going online, joining BTC Guild, and being taken off shortly thereafter.
Or it could be a combination of the two.
Ter any case, wij see no evidence that points to selfish mining ter this example. But this event calls for diligent monitoring of the blockchain dynamics from numerous vantage points.
Wij originally described the Selfish Mining attack on Bitcoin, where an attacker can spel Bitcoin and mine more than his fair share of coins.
Some members of the Bitcoin community, ter a madness to the moon, did not want to acknowledge that the Bitcoin protocol could be game-able and funded the development of an independent simulator whose subtext wasgoed to demonstrate the error of our ways. Interestingly, that simulator confirmed our findings.