While there is still no clear idea of who is responsible for the manipulation of ETC’s blockchain by controlling the majority of CPU power in the mining pool, the circumstances raise some big questions concerning the security and power of proof-of-work (PoW) algorithms.
It is worth taking a look at the chain of events leading up to the confirmation that ETC had indeed been the target of a blockchain reorganization.
A tweet from the ETC Twitter handle, which has since been deleted, speculated that testing of new 1,400/Mh ethash machines by application-specific integrated circuit (ASIC) manufacturer Linzhi may have been a potential cause.
ETC developers said that the attack was “most likely selfish mining,” noting that they had not detected any double spends at the time.
Coinbase had identified a “deep chain reorganization” of the ETC blockchain which included a double spend on Saturday, Jan. 5. By the evening of Jan. 7, the company had taken stock of multiple double spends on the network:
“At time of writing, we have identified a total of 15 reorganizations, 12 of which contained double spends,