The popular play-to-earn (P2E) NFT game Axie Infinity’s makers, Sky Mavis, have revealed that the Ronin bridge is now operational again, three months after it was compromised for more than $600 million.
Users can move assets between the sidechain and the Ethereum mainnet using the Ronin bridge, an Ethereum sidechain created for Axie Infinity.
The bridge was emptied of 173,600 ETH and 25.5 million USDC on March 29 after hackers were able to get private validator keys. At the time, the hack was worth more than $620 million.
Back online after a hiatus of 3 months
The Ronin newsletter provided more details about the restarting of the bridge. It said that the Ronin bridge is back online following three audits (one internal, two external), a fresh design, and complete restitution of users’ stolen assets, according to the June 28 release from the Sky Mavis team.
“All user funds are fully backed 1:1 by the new bridge. All users have been made whole.”
By providing the ETH liquidity to support users’ wrapped ETH (wETH) on the Ronin network, Sky Mavis has now refunded 117,600 ETH and 25.5 million USDC altogether.
Around 46,000 of those ETH had already been paid out as of April, thanks to Binance’s provision of a bridge to its exchange that allowed customers to convert their wETH to ETH. The founders’ cash and the balance at Axie Infinity were used to provide liquidity for the transaction. To assist Sky Mavis in paying back Axie Infinity users, Binance led a $150 million fundraising round.
The Axie DAO Treasury owns the remaining 56,000 of the total stolen ETH, which will continue to be uncollateralized as Sky Mavis “works with law police to retrieve the funds.”
New updates in the bridge architecture
Sky Mavis has updated the smart contract software as part of the updated bridge architecture to allow validators to establish daily withdrawal limitations, with the initial amount set at $50 million. The group also implemented a circuit breaker system that divides the number of withdrawals into three categories.
Tier 1 withdrawals under $1 million require the approval of 70% of validators, and Tier 2 withdrawals over $1 million demand the signatures of 90% of validators. Tier 3 calls for a 90 percent validator sign-off, a minor transaction charge, and a seven-day approval process for more than $10 million in withdrawals.
The circuit-breaker device is part of the new bridge design and acts as a backup plan to boost bridge security by stopping sizable suspicious withdrawals.
In a postmortem analysis published in late April, Sky Mavis acknowledged that the Ronin bridge had been exposed to the hack due to its lack of decentralization. It only had nine validator nodes at the moment, and four of them were accessible to employees.
Sky Mavis swiftly increased the number of nodes to 11, then stated plans to increase the number to 21 within three months of the autopsy, with the long-term objective of exceeding 100 total nodes.
In the most recent announcement, the team did not provide an update on the number of validator nodes the Ronin network now possesses.
According to data from CryptoSlam, Axie Infinity’s monthly NFT sales volume fell precipitously in 2022, from $126.4 million in January to barely $2.8 million in June.