Superbuilders Unify Siloed Chains
Nodekit is building Javelin—a superbuilder that enables cross chain composability, the silver bullet for solving cross chain fragmentation. Superbuilders simultaneously construct blocks across multiple chains. A user submits a set of transactions that are bundled together with the guarantee that either all the transactions will be executed or none will, enabling cross chain atomic transactions!
Atomic execution is possible across chains for the same reason it is possible on a single chain. There is one block producer that knows the prior state for the domains they are building for, and they have the ability to control the state changes included in the next block. Superbuilders run full nodes of all the chains for which they are building blocks. To verify that transactions will execute in the next block, builders simulate the state transitions on all chains. Any transactions that fail through the simulation are excluded, along with any bundled transactions associated with it.
ZK Faults Proofs Powered by SP1
Superbuilders provide optimistic guarantees of atomic composability between chains. Bundles of transactions are simulated to determine the validity of the bundled transactions before being included in the block.
Although the builder simulates transactions prior to submitting to ensure atomicity, the protocol must still be built to be robust to bundled transactions not being atomic. Builders are staked to provide economic security on the bundled transactions they are guaranteeing. In the case of a fault we need to slash the builders. And in order to prove faults we have to use Succinct’s SP1.
If a builder builds a block such that bundled transactions are not atomically executed, they are slashed. To prove a failed bundle has landed onchain, Javelin will leverage Succinct’s SP1-contract-call. SP1-contract-call is a simple way to generate a ZK-Proof of smart contract execution off chain that is cheaply verified onchain. With this integration, broken atomicity can be proven by proving a transaction was not included in a state root for a chain. This adds further security to provide safe, fast, and atomic cross-chain transactions.
A Future with Real Time ZK Proving
The future of ZK superbuilders doesn’t stop there. The current method of simulating transactions to ensure bundle validity is efficient and enables atomic execution guarantees, but can be improved. Better functionality and greater security can be unlocked through the use of real-time ZK proofs.
State changes can be proven at shorter intervals and the bundle settlement can happen quickly for chains, without needing to wait on settlement on Ethereum. With real-time proving coming into reality, state changes can be proven at shorter intervals and the bundle settlement can happen fastly on the side of rollup, without dependence on settlement on Ethereum.
This allows the end user to be confident that the bundle has executed atomically without any further integration into the chain. Chains are given a stronger guarantee of the validity of bundles by being provided a proof that the bundled transactions will all execute, with the ability to exclude bundled transactions that lack an accompanying proof.
With Succinct Labs’ acceleration towards cheap, real-time ZK proofs, and NodeKit’s focus on fast, atomic composability across chains, the ideal of single-block composability between chains provided by superbuilders, backed by the security of ZK proofs will soon become reality.