Over the previous weekend, on block 11380000, an answer for the prevention of 51% assaults was introduced to the Ethereum Basic (ETC) group. A number of such assaults have just lately positioned ETC at a crossroads, leaving the very survival of the chain unsure. Within the weeks that adopted these assaults, the group labored to guage quite a few potential options. 

The primary one which has been carried out is known as MESS, which stands for Modified Exponential Subjective Scoring. Its predecessor was first suggested by Vitalik Buterin again in 2014. It builds on the idea that whereas small chain reorganizations that return a couple of blocks are completely regular, those proposing reorganizations going again a whole lot and even 1000’s of blocks are extremely suspicious.

With most proof-of-work blockchains, the longest chain with essentially the most work wins. Which means malicious attackers should mine an extended chain in isolation after which, suggest it to the world. This was the case throughout current assaults, which price sincere individuals tens of millions of {dollars}.

MESS polynomial curve. Supply: Ethereum Classic Improvement Proposal 1100.

MESS disincentivizes shadow mining by weighing chains otherwise relying on the time of publication. Isaac Ardis, one in all ETC Core’s builders, defined this mechanism to Cointelegraph:

“The intention with that’s to weight chains which happen and can be found first over chains that come later. And so in that approach, there’s an incentive to publish work on the chain and it disincentivizes chains which might be outlined in personal and that might come later.”

The algorithm employs a multiplier that determines the required issue from a proposed chain to be able to be thought of canonical. The multiplier ranges from 1 to 31 and is dependent upon the aforementioned time of publication. The extra suspicious the proposed reorganization, the upper the multiplier. Thus a shadow chain must present manifold extra proof-of-work to be deemed canonical.

MESS doesn’t make 51% assaults not possible as it’s somewhat a probabilistic and never deterministic answer, nevertheless it makes them prohibitively costly. This is likely one of the explanation why the group has mentioned implementing it along side a checkpointing answer. Ardis stated that though it’s a chance, there doesn’t appear to be a lot profit to this duplication:

“Although you need to use them collectively, you could not have to make use of them collectively and should not even need to use them collectively.”

MESS has a number of benefits. The code base is compact and it’ll not require a tough fork to implement. The nodes that select to run MESS can be appropriate with those that don’t. Any discordance will solely come into play when and if one other 51% assault occurs, stated Ardis:

“If there’s a massive assault, then the miners, the operators and the nodes who’ve activated MESS, we actually hope, will efficiently dissuade the attacker whereas these nodes that have not upgraded would transfer to the attacker’s chain.”

The belief is that almost all of those assaults are typically short-termed and opportunistic. As soon as the attacker leaves, the remaining sincere miners will rejoin the canonical fork.

MESS seems to be a brief to mid-term answer. Though Ardis believes than no chain is immune from a 51% assault, he agreed that the one viable safety is the community’s development. One of many bets is on Ethereum (ETH) miners becoming a member of Ethereum Basic after the previous migrates to the proof-of-stake consensus. One other is making the most of the compatibility between the 2 networks, which permits for a painless migration from a congested Ethereum to Ethereum Basic. Ardis stated that now that they’re accomplished with this mess, the crew can give attention to growing new instruments for ETC.