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 (https://github.com/geohot/cannon).
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State validationIn development
Currently the system permits invalid state roots. More details in project overview.
Data availabilityOn chain
All of the data needed for proof construction is published on chain.
The code that secures the system can be changed arbitrarily and without notice.
Sequencer failureTransact using L1
The user is able to submit a transaction through L1 and force its inclusion on L2.
Validator failureNo mechanism
If the whitelisted validator goes down, no activity including withdrawals can happen. Funds will be frozen.
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).
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.
The system has a centralized sequencer
While proposing blocks 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-chain and anyone can submit their transactions there it allows the users to circumvent censorship by interacting with the smart contract directly.
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).
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.
The system uses the following set of permissioned addresses:
This address is the owner of the following contracts: OVM_L1CrossDomainMessenger, L1StandardBridge, LibAddressManager. This allows it to censor messages or pause message bridge altogether, upgrade 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).
These addresses are the participants of the 5/8 Optimism MultiSig.
Central actor allowed to commit L2 transactions to L1.
Central actor to post new L2 state roots to L1.
The system consists of the following smart contracts:
The Canonical Transaction Chain (CTC) contract is an append-only log of transactions which must be applied to the OVM state. It defines the ordering of transactions by writing them to the CTC:batches instance of the Chain Storage Container. CTC batches can only be submitted by OVM_Sequencer. The CTC also allows any account to enqueue() an L2 transaction, which the Sequencer must eventually append to the rollup state.
The State Commitment Chain (SCC) 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. Currenlty olny OVM_Proposer can submit new state roots.
The Bond Manager contract will handle deposits in the form of an ERC20 token from bonded Proposers. It will also handle the accounting of gas costs spent by a Verifier during the course of a challenge. In the event of a successful challenge, the faulty Proposer's bond will be slashed, and the Verifier's gas costs will be refunded. Current mock implementation allows only OVM_Proposer to propose new state roots. No slashing is implemented.
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.
This is a library that stores the mappings between names such as OVM_Sequencer, OVM_Proposer and other contracts and their addresses.
Main entry point forgetContract users depositing ERC20 tokens and ETH that do not require custom gateway. This contract can store any token
Custom SNX Gateway, main entry point for users depositing SNX to L2 where "canonical" L2 SNX token managed by Synthetix will be minted. Managed by Synthetix. This contract stores the following tokens: SNX.
SNX Vault for custom SNX Gateway managed by Synthetix. This contract stores the following tokens: SNX.
Custom DAI Gateway, main entry point for users depositing DAI to L2 where "canonical" L2 DAI token managed by MakerDAO will be minted. Managed by MakerDAO.
DAI Vault for custom DAI Gateway managed by MakerDAO. This contract stores the following tokens: DAI.
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).
Optimism’s Goerli Testnet migrated to Bedrock
2023 Jan 13th
OP on Goerli, since Jan 2023 is running Bedrock.Learn more
OP Stack Introduced
2022 Oct 17th
OP Stack, modular, open-sourced blueprint o how to build scalable blockchains.Learn more
OP token airdrop
2022 May 31st
The first round of OP token airdrop.Learn more
Mainnet for everyone
2021 Dec 16th
Whitelist got removed, there are no restrictions on who can transact with the network.Learn more
OVM 2.0 is live
2021 Nov 12th
Network upgrade to OVM 2.0 and removal of fraud-proof system.Learn more
2021 Aug 19th
All smart contracts allowed after prior approval.Learn more
Mainnet Soft Launch
2021 Jan 16th
Only selected contracts like Synthetix and Uniswap are available.Learn more