Offchain Labs Launches AnyTrust Chains: Cheaper and Faster L2 Chains

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Odaily资深作者

2022-03-03 05:27

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AnyTrust Chains will run alongside Arbitrum One

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AnyTrust Chains will run alongside Arbitrum One

This article is from Offchain Labs

Today we will announce a new network product route - AnyTrust chains, which is an arbitrum model with strong security guarantees and the advantages of extremely low transaction costs.

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AnyTrust Chains Background

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

However, under the application of some blockchains with special needs, especially in the field of games, some applications need to further reduce costs, or extract NFT faster. For these applications, we will introduce AnyTrust Chains, which allow for lower costs and faster withdrawals in exchange for minimal additional trust assumptions. The main advantage of AnyTrust over sidechains is that because it is built on top of Ethereum, AnyTrust requires far less trust. (We'll explain the details below.)

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AnyTrust Overview

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

This is an easier trust assumption than a traditional BFT sidechain, since maintaining a BFT sidechain requires more than 2/3 of the nodes to be honest — that would be 14 out of 20 people. 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, because nodes can rely on committees to provide data if required. And, in the case of the committee committing to the data, it is safe to simply record the hash of the batch of transactions on L1, saving the maximum cost of running rollups. Second, once the committee guarantees L1, withdrawals can be executed immediately.

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fallback to rollups

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why it is safe (given trust assumptions)

There are 20 committee members, of which at least 2 are honest, and anything signed by an arbitrator of 19 committee members must be correct, because there are at least two honest members, and only one member can be in In addition to the arbitration panel, the arbitration panel must contain an honest member. (In general, if there are N members and K honest members, the quorum can be any N+1-K members.)

Therefore, the arbitrator signed a promise about the data availability of a batch of transactions, and we can guarantee the data availability of these transactions - so we can only publish the transaction root hash on l1 instead of the full transaction hash.

Similarly, if the arbitrator signed a statement about a certain state, then the transaction state will be accepted directly without waiting for its long challenge period on l1.

None of these things would happen without an active panel of arbitrators willing to sign the statement. But that’s okay, the network can still update the network through Arbitrum’s rollups protocol, transaction data is published on Ethereum, and new rollups status is confirmed after the challenge period. Once the quorum is running again, the chain will seamlessly switch back to a more efficient and faster mode of operation.

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