Validium vs rollup
Polygon CDK running in validium mode inherits the core functionalities of a zkEVM rollup node and adds a data availability layer.
Key differences¶
| Rollup | Validium | |
|---|---|---|
| Node type | zkEVM node | Validium node: zkEVM node with validium extensions |
| Data availability | On-chain via L1 | Off-chain via a local option, or a DAC + DA node |
| Components | zkEVM components* | zkEVM components* + PostgreSQL database + on-chain committees |
| Contracts | zkEVM smart contracts
|
Validium-specific DAC contract
|
| Infrastructure | Standard infrastructure | Dedicated infrastructure for data availability layer and DACs |
| Tx flow | All transaction data is published on L1 | Validium only publishes the hash of the transaction data to L1. The sequencer sends both the hash and the transaction data to the DAC for verification. Once approved, the hash+signatures are sent to the Consensus L1 contract of the validium protocol. |
| Security | High security due to on-chain data availability and zero-knowledge proofs. | Off-chain data availability can affect security if the sequencer goes offline or if DAC members collude to withhold state data. |
| Gas fees | High, because all transaction data is stored on Ethereum. | Low, because only the hash of the transaction data is stored on Ethereum. |
| Proof generation | Uses Prover to generate proofs of batched transactions for validation. | Uses Prover to generate proofs of batched transactions for validation. |
| Final settlement | Transaction batches and their corresponding proofs are added to the Ethereum state. | The hash of transaction data and its proof are added to the Ethereum state, referred to as the consolidated state. |
*JSON RPC, Pool DB, Sequencer, Etherman, Synchronizer, State DB, Aggregator, Prover