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News Report

Ethereum Classic Devs Propose 51% Attack Prevention Protocol

2 mins
Updated by Ana Alexandre

In Brief

  • Ethereum Classic is ready to implement a new security upgrade in response to multiple 51% attacks.
  • The MESS system will reportedly prevent future malicious blockchain reorg attempts.
  • ETC dev team says MESS protocol respects the "code is law" philosophy.
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After multiple 51% attacks, Ethereum Classic (ETC) developers working towards making the project’s network more resistant to blockchain reorganization (reorg) exploits.
Proof-of-Work (PoW) blockchains with significantly smaller network effect remain vulnerable to malicious reorg attacks. Rogue actors can acquire the necessary computing power from hash rental services to launch these exploits.

ETC Security Upgrade Ready for Implementation

In a press release issued on Sept. 18, Ethereum Classic Labs (ETC Labs) announced a proposed plan to curb future 51% attacks. According to the press statement, ETC developers proposed the “Modified Exponential Subjective Scoring,” or MESS, system designed to prevent malicious blockchain reorgs. ETC Labs revealed that the MESS protocol already scaled the testing phase and will be available in the next ten days. The ETC dev team also revealed that work on the proposed solution involved the efforts of Web3 infrastructure firms Chainsafe and OpenRelay. MESS is reportedly an adaptation of the “Exponential Subjective Scoring” security framework proposed by Ethereum co-founder Vitalik Buterin back in 2014. According to ETC Labs, MESS prevents 51% attacks by red-flagging attempted large block reorgs as suspect. By so doing, these attacks become more expensive to propagate across the network. Indeed, the ETC dev team estimated that the malicious actors responsible for the August hack would have required $20 million in rented hash power. Data from — a website that displays the theoretical cost of a one-hour exploit on PoW chains — shows that rented hash power worth $3,900 at a hash rate of 2TH/s is sufficient to attack the ETC network for one hour. ETC developers say, with MESS deployed, hackers will require over 155 TH/s to mount such an attack.

MESS Solution Respects “Code is Law” Philosophy

Apart from enhancing the security of the network, ETC Labs said MESS respects the network’s “code is law” philosophy. According to the press release, the MESS protocol enables nodes to favor publicly propagated chains over private chain segments. Thus, secret chains developed by malicious actors will not be viable effectively terminating any attempt at a 51% attack. For ETC Labs founder, James Wo, implementing MESS will eliminate the need for exchanges to maintain long confirmation times for Ethereum Classic transactions. Commenting on the proposed security upgrade, Wo also remarked that MESS will stabilize the network and prevent miners from losing block rewards.


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