In a Core Devs assembly on Friday, Ethereum (ETH) builders mentioned potential measures that may very well be taken to forestall profitable 51% assaults from occurring.
The dialogue was impressed by this week’s 51% assaults on Ethereum Traditional (ETC) — a community that represents the unique state of Ethereum the place the implications of the DAO hack in 2016 weren’t reverted. The unique assault, which occurred between July 31 and Aug. 1, was revealed to be a rigorously orchestrated try at a double-spend that netted over $5 million in ETC to the attacker for a $200,000 funding in hashpower.
Through the name, Ethereum consumer builders mentioned if they need to take further measures towards these assaults and the way such measures must be applied.
Decreasing the reorg cap
A possible safety towards chain reorganization is organising checkpoints at a node stage which might set the historical past of the blockchain in stone after that time. Any proposed blockchain adjustments past this checkpoint would thus be rejected by nodes.
Chain reorganizations depend on mining an alternate model of the blockchain with a better quantity of hashpower than the commonly-accepted model. Because of the guidelines of Nakamoto consensus, the chain with a better accrued proof-of-work would mechanically change the unique when printed to nodes.
Peter Szilagyi, developer of the Geth consumer, mentioned that the software program already rejects reorganizations deeper than 90,000 blocks, or two weeks. That is nevertheless a lot larger than the efficient reorg that occurred in ETC of about 4,000 blocks.
Whereas reducing this threshold may assist defend from comparable assaults, Alexey Akhunov of OpenEthereum famous that caps set too low can have unexpected penalties.
Measures could also be ineffective
The depth of the ETC reorg was dictated partially by a historical past of earlier assaults. These led exchanges to massively elevate the affirmation threshold to simply accept deposits.
Szilagyi mentioned that for Ethereum, there isn’t a want for hundreds of blocks. Decentralized exchanges may very well be gamed by censoring transactions and maximizing the hacker’s buying and selling positive aspects with reorganizations of just some blocks. Setting a checkpoint cap that low could end in vital usability points. He added:
“I simply wished to spotlight that after you settle for that there are 51% assaults on the community, numerous issues begin breaking, as a result of numerous issues depend on the idea that you just can’t have deep reorgs.”
Tim Beiko, a developer at Ethereum growth firm PegaSys, famous that ETC’s case could also be completely different. Because of it being a a lot smaller and fewer precious chain, it’s simple to assemble the required hashpower to finish a 51% assault by one thing like Nicehash. This, to him, “is an even bigger concern than no matter shoppers implement by checkpoints.”
In the long run, builders agreed to debate the problems extra and assume by potential enhancements to Ethereum’s resilience.