zkSync, an Ethereum zero-knowledge Layer-2 scaling solution, is under fire from the cryptocurrency community due to allegations of insufficient measures against Sybil attacks during its recent token airdrop.
Critics argue that the distribution of its zkSync (ZK) tokens was poorly managed, allowing potential exploitation by those employing multiple wallets to unfairly claim tokens.
Mudit Gupta, Chief Information Security Officer at Polygon, voiced his criticism on June 11, describing the zkSync airdrop as "the most farmable and farmed airdrop ever."
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On the same day, zkSync announced that 695,232 wallets were eligible for the airdrop, outlining seven criteria aimed at preventing Sybil attacks; however, critics remained unconvinced of their effectiveness.
Adam Cochran, a partner at Cinneamhain Ventures, also criticized the eligibility criteria, claiming they were easy for legitimate users to miss and equally easy for Sybil attackers to meet.
Crypto analytics firm Nansen stepped in to clarify its role, stating it provided data on specific wallet segments, including those belonging to "whales and known scammers," but did not conduct anti-Sybil checks or advise on token allocations for the airdrop.
On the other hand, decentralized finance (DeFi) researcher Ignas noted that zkSync deliberately avoided strict anti-Sybil measures, as that could exclude genuine users through arbitrary filters.
Sybil Horror 6, a Sybil-tracking X account, used data from LayerZero Labs to estimate that 135 million ZK tokens might end up in Sybil wallets. Based on ZK's pre-market price on Aevo, these tokens could be worth up to $50 million.
The controversy surrounding the airdrop highlights the challenges of balancing fair distribution and effective Sybil attack prevention.
Matter Labs, the developer of zkSync, has also recently faced backlash for attempting to trademark the term "zero-knowledge" (ZK) in nine countries, which it later abandoned.
