Gravity
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About
Gravity is an Optimium built on the Orbit stack. It features onchain questing and has its own gas token - G. Other Galxe products are aiming to integrate with the L2 and a future migration to an L1 of the same name is planned.
Badges
About
Gravity is an Optimium built on the Orbit stack. It features onchain questing and has its own gas token - G. Other Galxe products are aiming to integrate with the L2 and a future migration to an L1 of the same name is planned.
Recategorisation
The project will be classified as "Other" due to its specific risks that set it apart from the standard classifications.
The project will move to Others because:
Consequence: projects without a sufficiently decentralized set of challengers rely on few entities to safely update the state. A small set of challengers can collude with the proposer to finalize an invalid state, which can cause loss of funds.
2024 Jul 09 — 2025 May 05
2024 May 18 — 2025 May 04
Funds can be stolen if
Funds can be lost if
MEV can be extracted if
No actor outside of the single Proposer can submit fraud proofs. Interactive proofs (INT) require multiple transactions over time to resolve. The challenge protocol can be subject to delay attacks. There is a 5d 14h challenge period.
Proof construction and state derivation fully rely on data that is posted on Celestia. Sequencer tx roots are checked against the Blobstream bridge data roots, signed off by Celestia validators.
There is no window for users to exit in case of an unwanted regular upgrade since contracts are instantly upgradable.
Anyone can become a Proposer after 11d 23h of inactivity from the currently whitelisted Proposers.
Data is posted to Celestia
Transactions roots are posted onchain and the full data is posted on Celestia. The blobstream bridge is used to verify attestations from the Celestia validator set that the data is indeed available.
Funds can be lost if the sequencer posts an unavailable transaction root (CRITICAL).
Funds can be lost if the data is not available on the external provider (CRITICAL).
Celestia
Updates to the system state can be proposed and challenged by a set of whitelisted validators. If a state root passes the challenge period, it is optimistically considered correct and made actionable for withdrawals.
Whitelisted validators propose state roots as children of a previous state root. A state root can have multiple conflicting children. This structure forms a graph, and therefore, in the contracts, state roots are referred to as nodes. Each proposal requires a stake, currently set to 0.1 ETH, that can be slashed if the proposal is proven incorrect via a fraud proof. Stakes can be moved from one node to one of its children, either by calling stakeOnExistingNode or stakeOnNewNode. New nodes cannot be created faster than the minimum assertion period by the same validator, currently set to 15m. The oldest unconfirmed node can be confirmed if the challenge period has passed and there are no siblings, and rejected if the parent is not a confirmed node or if the challenge period has passed and no one is staked on it.
Funds can be stolen if none of the whitelisted verifiers checks the published state. Fraud proofs assume at least one honest and able validator (CRITICAL).
A challenge can be started between two siblings, i.e. two different state roots that share the same parent, by calling the startChallenge function. Validators cannot be in more than one challenge at the same time, meaning that the protocol operates with partial concurrency. Since each challenge lasts 5d 14h, this implies that the protocol can be subject to delay attacks, where a malicious actor can delay withdrawals as long as they are willing to pay the cost of losing their stakes. If the protocol is delayed attacked, the new stake requirement increases exponentially for each challenge period of delay. Challenges are played via a bisection game, where asserter and challenger play together to find the first instruction of disagreement. Such instruction is then executed onchain in the WASM OneStepProver contract to determine the winner, who then gets half of the stake of the loser. As said before, a state root is rejected only when no one left is staked on it. The protocol does not enforces valid bisections, meaning that actors can propose correct initial claim and then provide incorrect midpoints.
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. After a delay of 1000d in which a Sequencer has failed to include a transaction that was directly posted to the smart contract, it can be forcefully included by anyone on the host chain, which finalizes its ordering.
Delayed forced transactions
To force transactions from the host chain, users must first enqueue “delayed” messages in the “delayed” inbox of the Bridge contract. Only authorized Inboxes are allowed to enqueue delayed messages, and the so-called Inbox contract is the one used as the entry point by calling the sendMessage or sendMessageFromOrigin functions. If the centralized sequencer doesn’t process the request within some time bound, users can call the forceInclusion function on the SequencerInbox contract to include the message in the canonical chain. The time bound is hardcoded to be 1000d.
Regular messaging
Autonomous exit
Users can (eventually) exit the system by pushing the transaction on L1 and providing the corresponding state root. The only way to prevent such withdrawal is via an upgrade.
EVM compatible smart contracts are supported
Arbitrum One uses Nitro technology that allows running fraud proofs by executing EVM code on top of WASM.
Ethereum
Roles:
Can submit transaction batches or commitments to the SequencerInbox contract on the host chain.
Can propose new state roots (called nodes) and challenge state roots on the host chain.
Actors:
- A Multisig with 4/10 threshold.
- Can act on behalf of UpgradeExecutor.
- Is allowed to interact with RollupProxy - Pause and unpause and set important roles and parameters in the system contracts: Can delegate Sequencer management to a BatchPosterManager address, manage data availability, DACs and the fastConfirmer role, set the Sequencer-only window, introduce an allowList to the bridge and whitelist Inboxes/Outboxes - acting via UpgradeExecutor.
- Can upgrade the implementation of Outbox, ChallengeManager, Bridge, Inbox, SequencerInbox, RollupEventInbox, UpgradeExecutor - acting via ProxyAdmin, UpgradeExecutor.
- Can upgrade the implementation of RollupProxy - acting via UpgradeExecutor.
Participants (10):
0x860e…c0530x5093…66280xA073…bda20xF331…647D0xF0B7…A4f00xa400…e6e40x3840…Fd5f0xa0C6…90380xefCf…dD5C0x4D80…5BAeUsed in:
Ethereum
Contract that allows challenging state roots. Can be called through the RollupProxy by Validators or the UpgradeExecutor.
A sequencer (registered in this contract) can submit transaction batches or commitments here.
Central contract for the project’s configuration like its execution logic hash (wasmModuleRoot) and addresses of the other system contracts. Entry point for Proposers creating new Rollup Nodes (state commitments) and Challengers submitting fraud proofs (In the Orbit stack, these two roles are both held by the Validators).
Implementation used in:
- Central contract defining the access control permissions for upgrading the system contract implementations.
- Can act on behalf of ProxyAdmin.
- Can be used to interact with RollupProxy - Pause and unpause and set important roles and parameters in the system contracts: Can delegate Sequencer management to a BatchPosterManager address, manage data availability, DACs and the fastConfirmer role, set the Sequencer-only window, introduce an allowList to the bridge and whitelist Inboxes/Outboxes.
- Can be used to upgrade implementation of RollupProxy.
Implementation used in:
One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.
This contract implements view only utilities for validators.
Proxy used in:
One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.
One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine. The source code of this contract is not verified on Etherscan.
One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.
Helper contract sending configuration data over the bridge during the systems initialization.
Implementation used in:
Can be used to upgrade implementation of Outbox, ChallengeManager, Bridge, Inbox, SequencerInbox, RollupEventInbox, UpgradeExecutor.
One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.
Value Secured is calculated based on these smart contracts and tokens:
Contract managing Inboxes and Outboxes. It escrows G sent to L2.
Implementation used in:
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).
Funds can be stolen if the source code of unverified contracts contains malicious code (CRITICAL).