Offchain Labs now offers an alternative to rollups for developers looking to launch on the Arbitrum network through Arbitrum Orbit.
Earlier this year, Arbitrum introduced Arbitrum Orbit, its own layer-3 development tool that enabled developers to launch their own chains on top of Arbitrum One, Arbitrum Nova and Arbitrum Goreli.
At the time, users in March could only launch Optimistic Rollups through Arbitrum Orbit.
Arbitrum Orbit rollup solutions post call data onto Ethereum through Arbitrum One, meaning that it receives security properties directly from the layer-1 solution itself. And multiple parties can participate in validating the rollup chain — making them entirely trustless and permissionless.
AnyTrust chains introduce an extra trust assumption in exchange for lower fees and faster withdrawals.
The extra trust assumption at work is a Data Availability Committee (DAC), or a permissioned group of member nodes that stores call data for a period of time, according to Matt Pearring, Offchain Labs product management lead.
“It’s significantly cheaper to do transaction on the network, we’re talking several orders of magnitude — if you have an example transaction on Arbitrum One that might be five to 20 cents, on an AnyTrust chain like Arbitrum Nova, these transactions are fractions of a cent,” Pearring told Blockworks.
Launching an Arbitrum Orbit AnyTrust chain means paying only Arbiturm fees, Lee Bousfield, tech lead at Offchain Labs, told Blockworks.
This means that data is posted onto the DAC, which issues a signature noting they have received the data only to the Arbitrum chain.
“The signature is a fixed size, and is much smaller than the full data itself, and just the signature is posted to Arbitrum, that’s why it saves so much cost,” Bousfield said. “Instead of posting all that data to Arbitrum, and then Arbitrum has to post all that data to Etheruem, an Arbitrum Orbit AnyTrust chain only has to post that small signature to Arbitrum.”
If a quorum on an AnyTrust chain cannot be reached, then it will operate as a regular rollup on Arbitrum Orbit.
Assembling your DAC
Arbitrum Nova currently has its own public DAC, Pearring said, but Orbit chains that want to launch an AnyTrust chain will have a few options for assembling their own “independently. “
Infrastructure providers, such as Caldera, have been working with teams to assemble a committee of DAC members.
“Teams have the flexibility to choose, and it depends where they want to pull those folks from,” Pearring said.
Arbitrum Orbit chains will be highly interoperable as the DAC is already trusted to store data, Bousfield said.
“If a quorum of them signs off on a message sent between chains, that would also be assumed to be correct because they’re already being trusted to store the data,” Bousfield said.
The data availability service, as such, can sign off on an assertion and skip the normal challenge period.
“If there’s a disagreement between the data availability members, then it will still go through the normal challenge process, but in most cases you’d expect messages to flow very quickly between Arbitrum Orbit chains and other Arbitrum chains,” he said.
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