The tweet revealed a potential cause for “the recent mining events,” attributing the increased hashrate to the testing of new 1,400/Mh ethash machines by application-specific integrated circuit (ASIC) manufacturer Linzhi.
Also today, major American cryptocurrency exchange Coinbase published a blog post revealing it had “detected a deep chain reorganization of the Ethereum Classic blockchain that included a double spend” on Jan. 5. The exchange proceeded to halt withdrawals and deposits of ETC, which have evidently not resumed by press time.
Coinbase also notes in the post that following the incident, it detected eight additional reorganization episodes that also included double spends, amounting to a reported 88,500 ETC (about $445,155 at press time).
Coinbase also specified that it was “not the target of this double spend and no funds were lost.”
On Jan. 7, cryptocurrency exchanges Coincheck and bitFlyer tweeted that they would be temporarily halting deposits and withdrawals of Ethereum Classic. Today, Jan. 8, at press time, bothexchanges noted on Twitter that the temporary pause is still in effect.
Chain reorganization is a situation when a single miner, or pool, has more resources than the rest of the network. The dominant miner can then define a new transaction history on the network by “pick[ing] an arbitrary previous block from which to extend an alternative block history.”