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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
  • PolygonZkEVM (main rollup contract)
  • PolygonZkEVMBridge
  • PolygonZkEVMGlobalExitRoot
Validium-specific DAC contract
  • CDKDataCommittee.sol
  • CDKValidium.sol
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


Last update: December 13, 2023
Authors: kmurphypolygon (50.0%), Nadim Kobeissi (11.11%), Niramisa Weiss (38.89%)