OP Mainnet
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About
OP Mainnet is an EVM-equivalent Optimistic Rollup. It aims to be fast, simple, and secure.
Badges
About
OP Mainnet is an EVM-equivalent Optimistic Rollup. It aims to be fast, simple, and secure.
Fallback to permissioned proposals for 26 days.
2024 Aug 16th
OP Mainnet preventively disables the fraud proof system due to a bug for 26 days.
OP Mainnet becomes Stage 1
2024 Jun 10th
OP Mainnet introduces fraud proofs and updates permissions.
Funds can be stolen if
MEV can be extracted if
Sequencer failure
Self sequenceState validation
Fraud proofs (INT)Fraud proofs allow actors watching the chain to prove that the state is incorrect. Interactive proofs (INT) require multiple transactions over time to resolve.
Exit window
NoneThere is no exit window for users to exit in case of unwanted regular upgrades as they are initiated by the Security Council with instant upgrade power and without proper notice.
OP Mainnet is a Fraud proofs ensure state correctness
After some period of time, the published state root is assumed to be correct. During the challenge period, anyone is allowed to submit a fraud proof that shows that the state was incorrect.
Funds can be stolen if no validator checks the published state. Fraud proofs assume at least one honest and able validator.
All data required for proofs is published on chain
All the data that is used to construct the system state is published on chain in the form of cheap blobs or calldata. This ensures that it will be available for enough time.
Data batches are compressed using the zlib algorithm with best compression level.
Updates to the system state can be proposed and challenged by anyone who has sufficient funds. If a state root passes the challenge period, it is optimistically considered correct and made actionable for withdrawals.
Proposers submit state roots as children of the latest confirmed state root (called anchor state), by calling the create function in the DisputeGameFactory. A state root can have multiple conflicting children. Each proposal requires a stake, currently set to 0.08 ETH, that can be slashed if the proposal is proven incorrect via a fraud proof. Stakes can be withdrawn only after the proposal has been confirmed. A state root gets confirmed if the challenge period has passed and it is not countered.
Challenges are opened to disprove invalid state roots using bisection games. Each bisection move requires a stake that increases expontentially with the depth of the bisection, with a factor of 1.09493. The maximum depth is 73, and reaching it therefore requires a cumulative stake of 691.43 ETH from depth 0. Actors can participate in any challenge by calling the defend or attack functions, depending whether they agree or disagree with the latest claim and want to move the bisection game forward. Actors that disagree with the top-level claim are called challengers, and actors that agree are called defenders. Each actor might be involved in multiple (sub-)challenges at the same time, meaning that the protocol operates with full concurrency. Challengers and defenders alternate in the bisection game, and they pass each other a clock that starts with 3d 12h. If a clock expires, the claim is considered defeated if it was countered, or it gets confirmed if uncountered. Since honest parties can inherit clocks from malicious parties that play both as challengers and defenders (see freeloader claims), if a clock gets inherited with less than 3h, it generally gets extended by 3h with the exception of 6h right before depth 30, and 1d right before the last depth. The maximum clock extension that a top level claim can get is therefore 10d. Since unconfirmed state roots are independent of one another, users can decide to exit with a subsequent confirmed state root if the previous one is delayed. Winners get the entire losers’ stake, meaning that sybils can potentially play against each other at no cost. The final instruction found via the bisection game is then executed onchain in the MIPS one step prover contract who determines the winner. The protocol does not enforce valid bisections, meaning that actors can propose correct initial claims and then provide incorrect midpoints. The protocol can be subject to resource exhaustion attacks (Spearbit 5.1.3).
The system has a centralized sequencer
While forcing transaction is open to anyone the system employs a privileged sequencer that has priority for submitting transaction batches and ordering transactions.
MEV can be extracted if the operator exploits their centralized position and frontruns user transactions.
Users can force any transaction
Because the state of the system is based on transactions submitted on the underlying host chain and anyone can submit their transactions there it allows the users to circumvent censorship by interacting with the smart contract on the host chain directly.
Regular exits
The user initiates the withdrawal by submitting a regular transaction on this chain. When a state root containing such transaction is settled, the funds become available for withdrawal on L1 after 3d 12h. Withdrawal inclusion can be proven before state root settlement, but a 7d period has to pass before it becomes actionable. The process of state root settlement takes a challenge period of at least 3d 12h to complete. Finally the user submits an L1 transaction to claim the funds. This transaction requires a merkle proof.
Forced exit
If the user experiences censorship from the operator with regular exit they can submit their withdrawal requests directly on L1. The system is then obliged to service this request or halt all withdrawals, including forced withdrawals from L1 and regular withdrawals initiated on L2. Once the force operation is submitted and if the request is serviced, the operation follows the flow of a regular exit.
EVM compatible smart contracts are supported
OP stack chains are 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 L2.
All contracts are upgradable by the SuperchainProxyAdmin which is controlled by a 2/2 multisig composed by the Optimism Foundation and a Security Council. The Guardian role is assigned to the Security Council multisig, with a Safe Module that allows the Foundation to act through it to stop withdrawals in the whole Superchain, blacklist dispute games, or deactivate the fault proof system entirely in case of emergencies. The Security Council can remove the module if the Foundation becomes malicious. The single Sequencer actor can be modified by the OpFoundationOperationsSafe via the SystemConfig contract. The SuperchainProxyAdminOwner can recover dispute bonds in case of bugs that would distribute them incorrectly.
At the moment, for regular upgrades, the DAO signals its intent by voting on upgrade proposals, but has no direct control over the upgrade process.
The system uses the following set of permissioned addresses:
Guardian is an actor allowed to pause deposits and withdrawals.
- OpFoundationUpgradeSafe has the role if the number of SecurityCouncilMultisig members falls below 8
- OpFoundationOperationsSafe has the role if not revoked by the Security Council
- Can change the configuration of LivenessModule - can remove members of SecurityCouncilMultisig inactive for 98d.
- Modular contract to be used together with the LivenessModule. Tracks liveness / activity of Safe owners.
Used in:
- A Gnosis Safe with 2 / 2 threshold.
- Can act on behalf of SuperchainProxyAdmin.
- Can change the configuration of AddressManager - set and change address mappings - acting via SuperchainProxyAdmin.
- Can upgrade the implementation of AnchorStateRegistry, DelayedWETH_PermissionedGames, SystemConfig, DelayedWETH_PermissionlessGames, L1ERC721Bridge, OptimismMintableERC20Factory, SuperchainConfig, OptimismPortal, DisputeGameFactory - acting via SuperchainProxyAdmin.
- Can upgrade the implementation of L1StandardBridge - upgrading the bridge implementation can give access to all funds escrowed therein - acting via SuperchainProxyAdmin.
Used in:
- A Gnosis Safe with 5 / 7 threshold.
- Member of SuperchainProxyAdminOwner.
- Can act on behalf of LivenessModule - takes ownership of SecurityCouncilMultisig if the number of SecurityCouncilMultisig members falls below 8.
- Can change the configuration of SystemConfig - it can update the preconfer address, the batch submitter (Sequencer) address and the gas configuration of the system.
- A Guardian - acting via GuardianMultisig, SecurityCouncilMultisig, LivenessModule if the number of SecurityCouncilMultisig members falls below 8.
Used in:
- A Gnosis Safe with 5 / 7 threshold.
- Can act on behalf of DeputyGuardianModule if not revoked by the Security Council.
- A Guardian - acting via GuardianMultisig, DeputyGuardianModule if not revoked by the Security Council.
Used in:
- A Gnosis Safe with 10 / 13 threshold. It uses the following modules: LivenessModule (used to remove members inactive for 98d while making sure that the threshold remains above 75%. If the number of members falls below 8, the OpFoundationUpgradeSafe takes ownership of the multisig).
- Member of GuardianMultisig, SuperchainProxyAdminOwner.
- A Guardian - acting via GuardianMultisig.
Participants (13):
0x07dC…d0730x0a12…58b80x1822…925e0x4A73…e61E0x51aC…3dDa0x5C0F…C47e0x6323…c8650x74FA…B3100x7ed8…9E390x8Afe…0EA40x9Eb1…fD7A0xbfA0…E0d90xE895…E514Used in:
- A Gnosis Safe with 1 / 1 threshold. It uses the following modules: DeputyGuardianModule (allows the OpFoundationOperationsSafe, called the deputy guardian, to act on behalf of the Gnosis Safe).
- Can act as a Guardian.
Participants (1):
SecurityCouncilMultisigUsed in:
- A Gnosis Safe with 2 / 2 threshold.
- Member of OpFoundationUpgradeSafe, OpFoundationOperationsSafe.
Used in:
A Sequencer.
The system consists of the following permissions on OP Mainnet:
- A Gnosis Safe with 3 / 5 threshold.
- Can change the configuration of MintManager - change the OP token owner to a different MintManager and therefore change the inflation policy.
Can upgrade the implementation of DeployerWhitelist, L2CrossDomainMessenger, GasPriceOracle, L2StandardBridge, SequencerFeeVault, OptimismMintableERC20Factory, L1BlockNumber, L2ERC721Bridge, L1Block, L2ToL1MessagePasser, OptimismMintableERC721Factory, L2ProxyAdmin, BaseFeeVault, L1FeeVault, SchemaRegistry, EAS - acting via L2ProxyAdmin.
The system consists of the following smart contracts on the host chain (Ethereum):
Custom Gateway for DAI deposits via canonical messaging. Deposited DAI is forwarded to a Vault contract.
Contains the latest confirmed state root that can be used as a starting point in a dispute game.
Upgrade delay: No delay
Contract designed to hold the bonded ETH for each game. It is designed as a wrapper around WETH to allow an owner to function as a backstop if a game would incorrectly distribute funds.
Upgrade delay: No delay
Implementation used in:
Sends messages from host chain to this chain, and relays messages back onto host chain. In the event that a message sent from host chain to this chain is rejected for exceeding this chain’s epoch gas limit, it can be resubmitted via this contract’s replay function.
Implementation used in:
Logic of the dispute game. When a state root is proposed, a dispute game contract is deployed. Challengers can use such contracts to challenge the proposed state root.
Contract designed to hold the bonded ETH for each game. It is designed as a wrapper around WETH to allow an owner to function as a backstop if a game would incorrectly distribute funds.
Upgrade delay: No delay
Implementation used in:
Stores DAI deposited from the attached L1DAITokenBridge. This contract stores the following tokens: DAI.
- Can be used to configure AddressManager - set and change address mappings.
- Can be used to upgrade implementation of AnchorStateRegistry, DelayedWETH_PermissionedGames, SystemConfig, DelayedWETH_PermissionlessGames, L1ERC721Bridge, OptimismMintableERC20Factory, SuperchainConfig, OptimismPortal, DisputeGameFactory.
- Can be used to upgrade implementation of L1StandardBridge - upgrading the bridge implementation can give access to all funds escrowed therein.
Implementation used in:
Used to bridge ERC-721 tokens from host chain to this chain.
Upgrade delay: No delay
Implementation used in:
Custom escrow for SNX bridged via canonical messaging. This contract stores the following tokens: SNX.
The MIPS contract is used to execute the final step of the dispute game which objectively determines the winner of the dispute.
Implementation used in:
A helper contract that generates OptimismMintableERC20 contracts on the network it’s deployed to. OptimismMintableERC20 is a standard extension of the base ERC20 token contract designed to allow the L1StandardBridge contracts to mint and burn tokens. This makes it possible to use an OptimismMintablERC20 as this chain’s representation of a token on the host chain, or vice-versa.
Upgrade delay: No delay
Implementation used in:
Lido custom escrow for wstETH tokens that uses the canonical bridge for messaging but is governed externally. This contract stores the following tokens: wstETH.
Same as FaultDisputeGame, but only two permissioned addresses are designated as proposer and challenger.
Used to manage global configuration values for multiple OP Chains within a single Superchain network. The SuperchainConfig contract manages the PAUSED_SLOT, a boolean value indicating whether the Superchain is paused, and GUARDIAN_SLOT, the address of the guardian which can pause and unpause the system.
Upgrade delay: No delay
Proxy used in:
The main entry point to deposit ERC20 tokens from host chain to this chain. This contract can store any token.
Upgrade delay: No delay
Implementation used in:
The PreimageOracle contract is used to load the required data from L1 for a dispute game.
Implementation used in:
The OptimismPortal contract is the main entry point to deposit funds from L1 to L2. It also allows to prove and finalize withdrawals. It specifies which game type can be used for withdrawals, which currently is the FaultDisputeGame. This contract stores the following tokens: ETH.
Upgrade delay: No delay
Implementation used in:
Legacy contract used to manage a mapping of string names to addresses. Modern OP stack uses a different standard proxy system instead, but this contract is still necessary for backwards compatibility with several older contracts.
Implementation used in:
The dispute game factory allows the creation of dispute games, used to propose state roots and eventually challenge them.
Upgrade delay: No delay
Implementation used in:
The system consists of the following smart contracts on OP Mainnet:
Legacy contract that was originally used to act as a whitelist of addresses allowed to the Optimism network. Fully unused and deprecated since the Bedrock upgrade.
Upgrade delay: No delay
The L2CrossDomainMessenger (L2xDM) contract sends messages from L2 to L1, and relays messages from L1 onto L2 with a system tx. In the event that a message sent from L2 to L1 is rejected for exceeding the L1 gas limit, it can be resubmitted via this contract’s replay function.
Upgrade delay: No delay
Upgrade delay: No delay
Upgrade delay: No delay
Upgrade delay: No delay
Contract used internally by the L2CrossDomainMessenger to send messages to L1, including withdrawals. It can also be used directly as a low-level interface.
Upgrade delay: No delay
Can be used to upgrade implementation of DeployerWhitelist, L2CrossDomainMessenger, GasPriceOracle, L2StandardBridge, SequencerFeeVault, OptimismMintableERC20Factory, L1BlockNumber, L2ERC721Bridge, L1Block, L2ToL1MessagePasser, OptimismMintableERC721Factory, L2ProxyAdmin, BaseFeeVault, L1FeeVault, SchemaRegistry, EAS.
Upgrade delay: No delay
Collects EIP-1559 base fees, which are withdrawable to the FeesCollector on L1.
Upgrade delay: No delay
Contracts to register schemas for the Ethereum Attestation Service (EAS).
Upgrade delay: No delay
Contract containing the main logic for the Ethereum Attestation Service (EAS).
Upgrade delay: No delay
The OP token contract. The minting policy is controlled by the MintManager.
Controls the OP inflation rate, which is currently hardcoded to 2% annually.
Value Secured is calculated based on these smart contracts and tokens:
Implementation used in:
Implementation used in:
DAI Vault for custom DAI Gateway managed by MakerDAO.
SNX Vault for custom SNX Gateway managed by Synthetix.
wstETH Vault for custom wstETH Gateway. Fully controlled by Lido governance.
The current deployment carries some associated risks:
Funds can be stolen if a contract receives a malicious code upgrade. Both regular and emergency upgrades must be approved by both the Security Council and the Foundation. There is no delay on regular upgrades.
