Read the new Layer 2 network launched by Offchain Labs: minimum trust, cheaper and faster

AnyTrust Chains Background
We really like Optimistic Rollups. Because they inherit the security of the underlying L1 chain (we take Ethereum as an example), while offering lower cost and higher throughput than L1. They can do this in an untrusted environment - anyone can push the correct update of the state of the chain. That's why we built Arbitrum One with Optimistic Rollup.

However, under some blockchain applications with special needs, especially in the field of gaming, some applications need to further reduce costs or extract NFTs faster. For these applications, we will introduce AnyTrust Chains, which allow for lower costs and faster withdrawals in exchange for a minimal assumption of additional trust.

The main advantage of AnyTrust compared to sidechains is that because it is built on Ethereum, AnyTrust requires far less trust. (We'll explain the details below.)

Before diving into it, we want to emphasize that Arbitrum One will maintain a trustless rollups scheme as always. We will continue to dedicate resources to improving the Arbitrum One protocol and ecosystem and will not stop our work on this.

For example, before launching AnyTrust Chains, we will release Arbitrum Nitro and upgrade Arbitrum One to Arbitrum Nitro. We're not giving up on trustless rollups - we're just introducing another option for those who need it.



AnyTrust Overview


Here are the gist of how AnyTrust works. The network is run by a committee of nodes with minimal assumptions about how many of the committee members are honest. For example, a committee might have 20 members, and it is assumed that at least two of them are honest.

This is an easier assumption of trust than traditional BFT sidechains, since maintaining a BFT sidechain requires more than 2/3 of the nodes to be honest — that would be 14 out of 20. Thanks to the "fallback to rollups" feature built on top of Ethereum, we can reduce the trust requirement from 14 to 2, as described below.

Assuming trust is established and committee members participate, users gain two major advantages. First, there is no need to record L2 transaction data on the L1 chain, as nodes can rely on the committee to provide data if needed.

And, with the committee committing to provide the data, it is safe to simply record the hash of the transaction batch on L1, saving the maximum cost of running rollups. Second, once the committee has secured L1, withdrawals can be executed immediately.

As long as 19 of the 20 committee members promise (by signing) that the deal is okay, both things can be done safely. The logic is that if there are at least 2 honest members, and 19 out of 20 people signed the pledge, then there is at least one honest member out of 19.