Optimism logoOptimism

  • Total value locked$1.62 B5.57%
  • Breakdown
  • Daily TPS5.3850.15%
  • 30D tx count9.26 M
  • TechnologyOptimistic Rollup
  • PurposeUniversal

    • ...

    Tokens:

    Milestones

    Optimism’s mainnet migration to Bedrock

    2023 Jun 6th

    OP mainnet, since Jun 2023 is running Bedrock.

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    Optimism’s Goerli Testnet migrated to Bedrock

    2023 Jan 13th

    OP on Goerli, since Jan 2023 is running Bedrock.

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    OP Stack Introduced

    2022 Oct 17th

    OP Stack, modular, open-sourced blueprint o how to build scalable blockchains.

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    OP token airdrop

    2022 May 31st

    The first round of OP token airdrop.

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    Mainnet for everyone

    2021 Dec 16th

    Whitelist got removed, there are no restrictions on who can transact with the network.

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    OVM 2.0 is live

    2021 Nov 12th

    Network upgrade to OVM 2.0 and removal of fraud-proof system.

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    Community Launch

    2021 Aug 19th

    All smart contracts allowed after prior approval.

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    Mainnet Soft Launch

    2021 Jan 16th

    Only selected contracts like Synthetix and Uniswap are available.

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    Knowledge Nuggets

    How Optimism compresses data

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    Bedrock Explainer

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    Modular Rollup Theory

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    Description

    Fraud proof system is currently under development. Users need to trust block Proposer to submit correct L1 state roots.

    Optimism Bedrock is an EVM-equivalent Optimistic Rollup chain. It aims to be fast, simple, and secure. With the Nov 2021 upgrade to OVM 2.0 old fraud proof system has been disabled while the new fraud-proof system is being built (https://github.com/ethereum-optimism/cannon).

    If you find something wrong on this page you can submit an issue or edit the information.

    Risk Analysis

    Sequencer failureState validationData availabilityUpgradeabilityProposer failure

    State validation

    In development

    Currently the system permits invalid state roots. More details in project overview.

    Data availability

    On chain

    All of the data needed for proof construction is published on chain.

    Upgradeability

    Yes

    The code that secures the system can be changed arbitrarily and without notice.

    Sequencer failure

    Self sequence

    In the event of a sequencer failure, users can force transactions to be included in the L2 chain by sending them to L1. There is a 12h delay on this operation.

    Proposer failure

    Cannot withdraw

    Only the whitelisted proposers can publish L2 state roots on L1, so in the event of failure the withdrawals are frozen.

    Technology

    Fraud proofs are in development

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

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

    1. L2OutputOracle.sol#L141 - Etherscan source code, deleteL2Outputs function

    All transaction data is recorded on chain

    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.

    1. Derivation: Batch submission - Optimism specs
    2. BatchInbox - Etherscan address
    3. OptimismPortal.sol#L434 - Etherscan source code, depositTransaction function

    Operator

    The system has a centralized operator

    The operator is the only entity that can propose blocks. A live and trustworthy operator is vital to the health of the system.

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

    1. L2OutputOracle.sol#L30 - Etherscan source code, CHALLENGER address
    2. L2OutputOracle.sol#L35 - Etherscan source code, PROPOSER address
    3. Decentralizing the sequencer - Optimism docs

    Users can force any transaction

    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.

    1. Sequencing Window - Optimism Specs
    2. OptimismPortal.sol#L434 - Etherscan source code, depositTransaction function

    Withdrawals

    Regular exit

    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.

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

    1. Withdrawing back to L1 - Optimism Help Center
    2. OptimismPortal.sol#L242 - Etherscan source code, proveWithdrawalTransaction function
    3. OptimismPortal.sol#325 - Etherscan source code, finalizeWithdrawalTransaction function
    4. L2OutputOracle.sol#L185 - Etherscan source code, PROPOSER check

    Other considerations

    EVM compatible smart contracts are supported

    Optimism is pursuing the EVM Equivalence model. No changes to smart contracts are required regardless of the language they are written in, i.e. anything deployed on L1 can be deployed on Optimism.

    1. Introducing EVM Equivalence

    Permissions

    The system uses the following set of permissioned addresses:

    OptimismMultisig 0x9BA6…6b3A

    This address is the owner of the following contracts: ProxyAdmin, SystemConfig. It is also designated as a Guardian of the OptimismPortal, meaning it can halt withdrawals, and as a Challenger for state roots. It can upgrade the bridge implementation potentially gaining access to all funds stored in a bridge and change the sequencer, state root proposer or any other system component (unlimited upgrade power). This is a Gnosis Safe with 5 / 7 threshold.

    OptimismMultisig participants 0x42d2…9c640x3041…16230xE7dE…d02e0xBF93…a2c80x4D01…6d150x7cB0…C54f0x9bbF…31aa

    Those are the participants of the OptimismMultisig.

    ProxyAdmin 0x543b…fB04

    Admin of the OptimismPortal, L2OutputOracle, SystemConfig contract, L1StandardBridge, AddressManager proxies. It’s controlled by the OptimismMultisig.

    Sequencer 0x6887…2985

    Central actor allowed to commit L2 transactions to L1.

    Proposer 0x4733…3A33

    Central actor to post new L2 state roots to L1.

    Challenger 0x9BA6…6b3A

    Central actor to challenge L2 state roots.

    Smart Contracts

    A diagram of the smart contract architecture
    A diagram of the smart contract architecture

    The system consists of the following smart contracts:

    L2OutputOracle 0xdfe9…5a27Implementation (Upgradable)Admin

    The L2OutputOracle contract contains a list of proposed state roots which Proposers assert to be a result of each transaction in the Canonical Transaction Chain (CTC). Elements here have a 1:1 correspondence with transactions in the CTC, and should be the unique state root calculated off-chain by applying the canonical transactions one by one. Currently only the PROPOSER address can submit new state roots.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    OptimismPortal 0xbEb5…06EdImplementation (Upgradable)Admin

    The OptimismPortal contract is the main entry point to deposit funds from L1 to L2. It also allows to prove and finalize withdrawals. This contract stores the following tokens: ETH.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    L1CrossDomainMessengerProxy 0x25ac…5fA1Implementation (Upgradable)

    The L1 Cross Domain Messenger (L1xDM) contract sends messages from L1 to L2, and relays messages from L2 onto L1. In the event that a message sent from L1 to L2 is rejected for exceeding the L2 epoch gas limit, it can be resubmitted via this contract's replay function.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    SystemConfig 0x2290…B290Implementation (Upgradable)Admin

    It contains configuration parameters such as the Sequencer address, the L2 gas limit and the unsafe block signer address.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    TVL is calculated based on these smart contracts and tokens:

    Generic escrow 0x99C9…4bE1Implementation (Upgradable)Admin

    Main entry point for users depositing ERC20 tokens that do not require custom gateway.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Escrow for ETH 0xbEb5…06EdImplementation (Upgradable)Admin

    Main entry point for users depositing ETH.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Escrow for DAI 0x4671…6C65

    DAI Vault for custom DAI Gateway managed by MakerDAO.

    Escrow for SNX 0x5Fd7…eF9f

    SNX Vault for custom SNX Gateway managed by Synthetix.

    Tokens: OP

    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).