Two bitcoin money (BCH) mining swimming pools not too long ago carried out what is called a 51 p.c assault on the blockchain in an obvious effort to reverse one other miner’s transactions.
The transfer is tied to the bitcoin money community arduous fork that occurred on Could 15. The 2 mining swimming pools — BTC.com and BTC.prime — carried out the transfer in an effort to cease the unknown miner from taking cash that they weren’t presupposed to have entry to within the wake of the code change. That day, an attacker took benefit of a bug unrelated to the improve (and subsequently patched) that precipitated the community to separate and for miners to mine empty blocks for a short time.
Within the context of cryptocurrencies like bitcoin money, a 51 p.c assault includes an entity or group controlling a majority of the hash fee which thereby permits them to execute a number of issues they aren’t usually allowed to do, equivalent to making an attempt to rewrite the community’s transaction historical past.
At one level BTC.prime did alone control more than 50% of the power. However BTC.com and BTC.prime they had been capable of be a part of collectively to reverse the blocks of transactions. In line with stats site Coin.Dance, the 2 mining swimming pools at present have mixed 44% of bitcoin money hashing energy.
The fascinating a part of this specific assault on bitcoin money, although, is that it was arguably executed in an try to do one thing ostensibly good for the neighborhood, to not reward the attackers or to take the funds for themselves.
However not everybody within the bitcoin money neighborhood agrees. As one bitcoin money developer, going by the moniker Kiarahpromises, put it in an article from Could 17:
“To coordinate a reorg to revert unknown’s transactions. This can be a 51% assault. The completely worst assault doable. It’s there within the whitepaper. What about (miner and developer) decentralized and uncensorable money? Solely when handy?”
Anatomy of an assault
The inside particulars of the mining swimming pools’ assault (in addition to the assault that prompted the assault) are difficult.
“Because the authentic cut up in 2017, there was a big variety of cash by chance despatched to ‘anybody can spend’ addresses (as a result of [transaction] compatibility of sigs, however no #SegWit on #BCH), or presumably they’ve been replayed from #Bitcoin onto the #BCH community,” bitcoin podcast host Man Swann stated, explaining the scenario on Twitter.
However as soon as one code change was eliminated throughout bitcoin money’s Could 15 arduous fork, these cash had been all of a sudden spendable “mainly handing the cash to miners,” he added.
The unknown miner attacker determined to attempt to take the cash. That’s when BTC.prime and BTC.com swooped in to reverse these transactions.
“When the unknown miner tried to take the cash themselves, [BTC.top and BTC.com] noticed & instantly determined to re-organize and take away these [transactions], in favor of their very own [transactions], spending the identical P2SH cash, [and] many others,” Swann went on.
However some bitcoin money customers argue this was the appropriate factor to do.
“This can be a very unlucky scenario, however it is usually what proof of labor really is. The miners on this case did select to drop prohashes block and from what I heard, it’s as a result of they deemed a transaction inside it to have been invalid,” responded energetic bitcoin money supporter Jonathan Silverblood.
Nonetheless, others assume that this can be a unhealthy signal for bitcoin money, arguing that the occasion demonstrates that the cryptocurrency is just too centralized.
But the thread of a 51 p.c assault is a priority shared throughout proof-of-work crypto networks (and as talked about above, some blockchains have been left uncovered as a result of falling hash charges). For instance, half of bitcoin’s present hashing energy is split amongst just three mining pools in response to stats web site Blockchain.
Mining software program picture through Shutterstock
This text has been up to date for readability.