Parallel
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Parallel is an Ethereum L2 solution utilizing Arbitrum Nitro technology.
$155.93 K
9.50%
- Fraud proof submission is not sufficiently decentralized.
- Upgrades executed by actors with more centralized control than a Security Council provide less than 7d for users to exit if the permissioned operator is down or censoring.
- The Security Council is not properly set up.
Badges
About
Parallel is an Ethereum L2 solution utilizing Arbitrum Nitro technology.
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ArbOS v20 upgrade
2024 Apr 10th
Introduces EIP-4844 data blobs for L1 data availability and Dencun-related opcodes on L2.
Funds can be stolen if
Funds can be lost if
MEV can be extracted if
State validation
Fraud proofs (INT)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 6d challenge period.
Exit window
NoneThere is no window for users to exit in case of an unwanted regular upgrade since contracts are instantly upgradable.
Sequencer failure
Self sequenceProposer failure
Self proposeAnyone can become a Proposer after 6d 8h of inactivity from the currently whitelisted Proposers.
![Parallel](/icons/parallel.png)
- A complete and functional proof system is deployed.
- Users are able to exit without the help of the permissioned operators.
- Fraud proof submission is not sufficiently decentralized.
- Upgrades executed by actors with more centralized control than a Security Council provide less than 7d for users to exit if the permissioned operator is down or censoring.
- The Security Council is not properly set up.
- Fraud proof submission is open only to whitelisted actors.
- Upgrades unrelated to on-chain provable bugs provide less than 30d to exit.
- The Security Council’s actions are not confined to on-chain provable bugs.
Fraud proofs ensure state correctness
After some period of time, the published state root is assumed to be correct. For a certain time period, one of the whitelisted actors can submit a fraud proof that shows that the state was incorrect. The challenge protocol can be subject to delay attacks.
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).
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.
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-chain and anyone can submit their transactions there it allows the users to circumvent censorship by interacting with the smart contract directly. Anyone can become a Proposer after approximately 6d 8h (45818 blocks) of inactivity from the currently whitelisted Proposers.
Regular exit
The user initiates the withdrawal by submitting a regular transaction on this chain. 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.
Tradeable Bridge Exit
When a user initiates a regular withdrawal a third party verifying the chain can offer to buy this withdrawal by paying the user on L1. The user will get the funds immediately, however the third party has to wait for the block to be finalized. This is implemented as a first party functionality inside Arbitrum’s token bridge.
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.
Funds can be lost if there are mistakes in the highly complex Nitro and WASM one-step prover implementation.
The system uses the following set of permissioned addresses:
Central actors allowed to submit transaction batches to L1.
They can submit new state roots and challenge state roots. Some of the operators perform their duties through special purpose smart contracts.
Multisig that can execute upgrades via the UpgradeExecutor. This is a Gnosis Safe with 4 / 7 threshold.
Those are the participants of the ConduitMultisig.
EOA that can execute upgrades via the UpgradeExecutor.
![A diagram of the smart contract architecture](/images/architecture/parallel.png)
The system consists of the following smart contracts on the host chain (Ethereum):
Router managing token <–> gateway mapping.
Main contract implementing Arbitrum One Rollup. Manages other Rollup components, list of Stakers and Validators. Entry point for Validators creating new Rollup Nodes (state commits) and Challengers submitting fraud proofs.
Contract managing Inboxes and Outboxes. It escrows the native token used for gas on the chain. This contract stores the following tokens: ETH.
Main entry point for the Sequencer submitting transaction batches.
Contract allowed to upgrade the system.
Contract that allows challenging invalid state roots. Can be called through the RollupProxy.
Contract used to perform the last step of a fraud proof.
Contract used to perform the last step of a fraud proof.
Contract used to perform the last step of a fraud proof.
Contract used to perform the last step of a fraud proof.
Contract used to perform the last step of a fraud proof.
Value Locked is calculated based on these smart contracts and tokens:
Main entry point for users depositing ERC20 tokens. Upon depositing, on L2 a generic, “wrapped” token will be minted.
Main entry point for users depositing ERC20 tokens that require minting custom token on L2.
Contract managing Inboxes and Outboxes. It escrows ETH sent to L2.
Upgrade delay: No delay
Escrow for WETH sent to L2.
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).