Boba Network
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Milestones
Call data compression
2022 Oct 8th
The Boba Tree From (v0.1.0) release introduces Brotli compression for call data.
Learn moreHybrid Compute
2022 Mar 18th
Boba’s proprietary technology enables dApps that trigger code executed on web-scale infrastructure.
Learn moreMainnet launch
2021 Sep 20th
Layer 2 Optimistic Rollup based on the Optimism codebase is live on Ethereum.
Learn moreKnowledge Nuggets
Description
Boba is an L2 Ethereum scaling & augmenting solution built by the Enya team as core contributors to the Boba Foundation. Boba is an EVM-compatible Optimistic Rollup chain forked from Optimism. Two notable features are fast withdrawal facility that allows users to remove funds immediately without waiting for the end of the 7-day fraud proof window. This facility is using funds from liquidity providers. The second is Hybrid Compute technology that enables Ethereum developers to build dApps that trigger code executed on web-scale infrastructure. Boba Network operates on multiple Layer 1 blockchains.
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Risk Analysis
State validation
In developmentCurrently the system permits invalid state roots. More details in project overview.
Data availability
On chainAll of the data needed for proof construction is published on chain.
Upgradeability
YesThe code that secures the system can be changed arbitrarily and without notice.
Sequencer failure
Enqueue via L1Users can submit transactions to an L1 queue, but can't force them. The sequencer cannot selectively skip transactions but can stop processing the queue entirely. In other words, if the sequencer censors or is down, it is so for everyone.
Proposer failure
Cannot withdrawOnly 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 Boba Network will use fraud proofs to enforce state correctness. This feature is currently in development and the system permits invalid state roots. Users have the ability to run a validator software and compute valid state roots locally, but cannot act on them on chain.
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.
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.
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.
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).
Fast exit
Users can initiate a fast exit which makes use of liquidity pools, and charges a small fee for the convenience. Users funds can then be withdrawn on L1 after only minutes.
Other considerations
EVM compatible smart contracts are supported
Boba Network 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 Boba Network.
Permissions
The system uses the following set of permissioned addresses:
This address is the owner of the following contracts: OVM_L1CrossDomainMessenger, L1StandardBridge, AddressManager. 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).
Central actor allowed to commit L2 transactions to L1.
Central actor to post new L2 state roots to L1.
Smart Contracts
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.
Can be upgraded by: Owner
Upgrade delay: No delay
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. Currently only OVM_Proposer can submit new state roots.
Can be upgraded by: Owner
Upgrade delay: No delay
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.
Can be upgraded by: Owner
Upgrade delay: No delay
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. The contract is pausable by Owner.
Can be upgraded by: Owner
Upgrade delay: No delay
The L1 Cross Domain Messenger (L1xDM) contract that allows permissioned relayer to relay messages from L2 onto L1 immediately without waiting for the end of the fraud proof window. It is used only for L2->L1 communication. The contract is pausable by Owner.
Can be upgraded by: Owner
Upgrade delay: No delay
Helper contract that allows for relaying a batch of messages using L1CrossDomainMessenger.
Can be upgraded by: Owner
Upgrade delay: No delay
Helper contract that allows for relaying a batch of messages using L1CrossDomainMessengerFast.
Can be upgraded by: Owner
Upgrade delay: No delay
Liquidity Pool manager for fast withdrawal facility. This contract can store any token.
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 for users depositing ERC20 tokens and ETH that do not require custom gateway. This contract can store any token.
Can be upgraded by: Owner
Upgrade delay: No delay
Standard NFT bridge. The contract is pausable by Owner.
Can be upgraded by: Owner
Upgrade delay: No delay
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).