Ethereum zero-knowledge layer-2 scaling platform zkSync has continued to defend criticism over the criteria for its zkSync (ZK) token airdrop, slated to launch on June 17.

In a frequently asked questions (FAQ) document updated on June 15, ZK Nation answered 15 questions mostly aimed at explaining why some groups were eligible for the token while others weren’t.

One of its longer answers focused on its detection and prevention measures for Sybil attacks — when one entity creates and uses a large number of wallets to farm an airdrop — a continuing pain point among airdrop claimants last week.

ZkSync reiterated it had used “explicit” Sybil detection in addition to a “unique airdrop design” to ensure the highest number of organic users were rewarded, but it also noted that this has led to some Sybil wallets being let through.

It explained some Sybils can employ sophisticated algorithmic strategies that are indistinguishable from real people.

“They fund accounts from many distinct exchange addresses, never interact with each other, use randomized amounts, and use software to randomize daily patterns of human behavior, and even perform activities unique to the project (for example, using zkSync paymasters),” it explained.

“The majority of such bots are completely undetectable, even with the most advanced anti-Sybil methodology.”

ZkSync claimed being too aggressive with filtering could eliminate some Sybils but also might falsely flag many organic users — so it chose to reward organic users with “high likelihood” by using a combination of value scaling and multipliers.

Essentially, this assigned fewer eligibility points to wallets with low funding (a sign of Sybil behavior) but would give them a multiplying boost if there was onchain behavior that signaled human behavior.

ZkSync explained that Sybils typically creates many accounts but uses small amounts of crypto to fund each account to be capital efficient.

Introducing the ZK Token

Checker → https://t.co/O2UonCvfzi
Announcement → https://t.co/hjgI14PHoi
Docs → https://t.co/taWBoCnfbc

It’s time to put the ZK token into the hands of the community. It’s your turn to govern ZKsync’s future. pic.twitter.com/VD3fZgH5bf

— ZK Nation (@TheZKNation) June 11, 2024

“Real people, on the other hand, tend to concentrate most of their wealth in just a few accounts, making their balances much larger compared to bots,” it explained. 

“There will be Sybils in every airdrop,” it concluded. “However, for every example of Sybil that can be identified, there are hundreds that were excluded.”

Binance offers ZK listing and distribution amid “ongoing concerns”

It comes as crypto exchange Binance has offered its own ZK airdrop — targeted at those who were not eligible for the official airdrop on June 17.

The exchange said it will offer 10.5 million ZK tokens to over 52,000 Binance users in “light of the ongoing concerns from the community around ZK token distribution.”

Related: Ethereum scaling ecosystem’s combined TPS hits new all-time high

Eligible claim addresses need to have initiated at least 50 transactions on zkSync Era between February 2023 and March 2024, conducted transactions in at least seven months in that period, aren’t a CEX, bridge or contract address and weren’t eligible for the official airdrop.

However, each Binance user will only be given 200 ZK each.

The exchange will also open the ZK token for trading from June 17, including trading pairs with Bitcoin (BTC), Tether (USDT) and First Digital USD (FDUSD).

The ZK token airdrop will launch on June 17. According to Whales Pro, the ZK token is currently trading pre-market for 36 cents.

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