Would any well-intended miner propose a deep chain reorganization?
Earlier today, Dexaran presented its solution to the Ethereum Classic (ETC) community aimed at preventing future 51% attacks. The presentation came a week after Cardano’s IOHK introduced its checkpointing proposal. Dexaran notably used IOHK’s Crowdcast channel for its competing solution.
This new proposal is founded on the assumption that many 51% attacks involve so-called "stealth mining", where an attacker, in isolation, would secretly mine a longer fork of the chain. This technique was used in a recent attack on the ETC, which cost OKEx $5.6 million.
The proposal hinges on the premise that a well-intended miner is unlikely to advance a chain that requires a deep reorganization of the network. Typically, "honest" forks involve a single block or, sometimes, a handful of blocks. One of Dexaran’s presenters specified:
“What this proposes is that, say, there shouldn't be any reorganization deeper than one hundred blocks.”
One of the major purported advantages of this solution is that it requires very little coding and can be implemented quickly. Another advantage is that it has been implemented by several other projects. In addition, the Dexaran team believes that their solution could be a stepping stone to the IOHK’s checkpointing solution, which requires more time due to its complexity. We asked the team why, if their solution is capable of preventing 51% attacks on the network, there would still be a need for the IOHK’s solution? They said:
“We do believe is that because it's a proven solution and it's a tested solution and it's really simple to implement, we do believe it will just simply provide the necessary time to be able to implement more complex solutions like the checkpointing system that was proposed.”
Next week, RSK is expected to present an update based on Bitcoin’s merged mining.