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Optimism logoOptimism

TVL: $423 M

-13.00% / 7 days






Currently only whitelisted contracts can be deployed on Optimism.

Optimistic Ethereum is an EVM-compatible Optimistic Rollup chain. It aims to be fast, simple, and secure. With the Nov 2021 upgrade to "EVM equivalent" OVM 2.0 old fraud proof system has been disabled while the new fraud-proof system is being built.

Risk summary


Fraud proofs are in development[Edit][Issue]

Ultimately Optimism will use interactive fraud proofs to enforce state correctness. This feature is currently in development and the system permits invalid state roots.[1]

  • Funds can be stolen if an invalid state root is submitted to the system (CRITICAL).

All transaction data is recorded on chain[Edit][Issue]

All executed transactions are submitted to an on chain smart contract. The execution of the rollup is based entirely on the submitted transactions, so anyone monitoring the contract can know the correct state of the rollup chain.[2]


    The system has a centralized sequencer[Edit][Issue]

    While proposing blocks is open to anyone the system employs a privileged sequencer that has priority for submitting transaction batches and ordering transactions.[3]

    • MEV can be extracted if the operator exploits their centralized position and frontruns user transactions.

    Users can force any transaction[Edit][Issue]

    Because the state of the system is based on transactions submitted on-chain and anyone can submit their transactions there it allows the users to circumvent censorship by interacting with the smart contract directly.[4]


      Regular exit[Edit][Issue]

      The user initiates the withdrawal by submitting a transaction on L2. When the block containing that transaction is finalized the funds become available for withdrawal on L1. The process of block finalization usually takes several days to complete. Finally the user submits an L1 transaction to claim the funds. This transaction requires a merkle proof.[6]

      • Funds can be frozen if the centralized validator goes down. Users cannot produce blocks themselves and exiting the system requires new block production (CRITICAL).[5]

      Other considerations

      EVM compatible smart contracts are supported[Edit][Issue]

      Optimism uses the Optimistic Virtual Machine (OVM) to execute transactions. This is similar to the EVM, but is independent from it and allows fraud proofs to be executed. Currently there is a whitelist that limits who can deploy smart contracts.[7]

      • Funds can be lost if there are mistakes in the highly complex OVM implementation.

      Smart Contracts[Edit][Issue]

      The system consists of the following smart contracts:

      The current deployment carries some associated risks:

      • Funds can be stolen if a contract receives a malicious code upgrade. There is no delay on code upgrades (CRITICAL).


      1. Introducing EVM Equivalence
      2. Data Availability Batches - Paradigm Research
      3. How will the sequencer be decentralized over time? - Optimism documentation
      4. Chain Contracts - Optimism documentation
      5. mockOVM_BondManager.sol#L71 - Etherscan source code
      6. Withdrawing back to L1 - Optimism documentation
      7. Deployer Whitelist - Optimism documentation