# Parallel

Markdown version of https://ethbeat.org/layer2s/projects/parallel

## Summary

**Warning:** This project is archived and no longer maintained.

**Warning:** Parallel is [deprecating their Orbit stack Layer 2](https://medium.com/@ParallelFi/the-withdrawal-on-parallel-l2-is-now-available-c3b4b572864e).

**Warning:** Critical contracts can be upgraded by an EOA which could result in the loss of all funds.

**Warning:** Why is the project listed in others? The proof system isn't fully functional. Consequence: projects without a proper proof system fully rely on single entities to safely update the state. A malicious proposer can finalize an invalid state, which can cause loss of funds. Learn more about the [recategorisation](https://medium.com/l2beat/framework-update-l2-projects-recategorisation-5d43b0d1fe50).

- Total Value Secured: $1.17 (-2.47% compared to seven days ago; canonically bridged $1.17, natively minted $0.00, externally bridged $0.00; 0.00% with additional trust assumptions compared to the tokens involved and the Stage assigned to the project's canonical messaging bridge)
- TVS by asset: ETH & derivatives $1.17 (100%)
- Past day UOPS: No data
- Gas token: ETH
- Type: Other
- Purpose: Universal
- Host chain: Ethereum
- Chain ID: 1024

### Risks

- Sequencer failure: Self sequence (2d delay; sentiment: good)
- State validation: Fraud proofs (INT) (6d challenge period; sentiment: bad)
- Data availability: Onchain (sentiment: good)
- Exit window: None (sentiment: bad)
- Proposer failure: Self propose (12d 8h delay; sentiment: good)

### About

Parallel is an Ethereum L2 solution utilizing Arbitrum Nitro technology.

### Links

- Website: https://parallel.fi
- Bridge: https://parallel.fi/airdrop
- Docs: https://docs.parallel.fi/parallel-chain/overview
- Explorer: https://explorerl2new-surprised-harlequin-bonobo-fvcy2k9oqh.t.conduit.xyz/
- Social: https://twitter.com/ParallelFi, https://discord.com/invite/parallelfi, https://t.me/parallelfi_community
- Contracts explorer (Disco): https://disco.ethbeat.org/ui/p/parallel

### Badges

- EVM: This project uses the Ethereum Virtual Machine to run its smart contracts and supports the Solidity programming language
- Ethereum with calldata: This project is posting its data to Ethereum as calldata
- Built on Arbitrum Orbit: The project is built on Arbitrum Orbit

## Value Secured

The interactive TVS charts are shown on [the HTML page](https://ethbeat.org/layer2s/projects/parallel#tvs).

Token by token: [TVS breakdown](https://ethbeat.org/layer2s/projects/parallel/tvs-breakdown).

- [TVS chart (JSON)](https://ethbeat.org/api/scaling/tvs/parallel?range=max)
- [TVS breakdown by token (JSON)](https://ethbeat.org/api/scaling/tvs/parallel/breakdown)

## Activity

The interactive activity chart is shown on [the HTML page](https://ethbeat.org/layer2s/projects/parallel#activity).

- [Activity chart (JSON)](https://ethbeat.org/api/scaling/activity/parallel?range=max)

## Onchain costs

The section shows the operating costs that L2s pay to Ethereum.

The interactive costs chart is shown on [the HTML page](https://ethbeat.org/layer2s/projects/parallel#onchain-costs).

### Tracked transactions

#### Batch submissions

- functionCall: 2024-01-01 16:18 UTC - now; currently used; address: [0xb4795A0edae98d7820C37F06f6b858e7acb51DF8](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8); selector: 0xe0bc9729; signature: `function addSequencerL2Batch(uint256 sequenceNumber,bytes calldata data,uint256 afterDelayedMessagesRead,address gasRefunder,uint256 prevMessageCount,uint256 newMessageCount)`
- functionCall: 2024-01-01 16:18 UTC - now; currently used; address: [0xb4795A0edae98d7820C37F06f6b858e7acb51DF8](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8); selector: 0x8f111f3c; signature: `function addSequencerL2BatchFromOrigin(uint256 sequenceNumber,bytes data,uint256 afterDelayedMessagesRead,address gasRefunder,uint256 prevMessageCount,uint256 newMessageCount)`
- functionCall: 2024-01-01 16:18 UTC - now; currently used; address: [0xb4795A0edae98d7820C37F06f6b858e7acb51DF8](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8); selector: 0x69cacded; signature: `function addSequencerL2BatchFromOriginDelayProof(uint256 sequenceNumber, bytes data, uint256 afterDelayedMessagesRead, address gasRefunder, uint256 prevMessageCount, uint256 newMessageCount, tuple(bytes32 beforeDelayedAcc, tuple(uint8 kind, address sender, uint64 blockNumber, uint64 timestamp, uint256 inboxSeqNum, uint256 baseFeeL1, bytes32 messageDataHash) delayedMessage) delayProof)`
- functionCall: 2024-01-01 16:18 UTC - now; currently used; address: [0xb4795A0edae98d7820C37F06f6b858e7acb51DF8](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8); selector: 0x917cf8ac; signature: `function addSequencerL2BatchFromBlobsDelayProof(uint256 sequenceNumber, uint256 afterDelayedMessagesRead, address gasRefunder, uint256 prevMessageCount, uint256 newMessageCount, tuple(bytes32 beforeDelayedAcc, tuple(uint8 kind, address sender, uint64 blockNumber, uint64 timestamp, uint256 inboxSeqNum, uint256 baseFeeL1, bytes32 messageDataHash) delayedMessage) delayProof)`
- functionCall: 2024-01-01 16:18 UTC - now; currently used; address: [0xb4795A0edae98d7820C37F06f6b858e7acb51DF8](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8); selector: 0x3e5aa082; signature: `function addSequencerL2BatchFromBlobs(uint256 sequenceNumber,uint256 afterDelayedMessagesRead,address gasRefunder,uint256 prevMessageCount,uint256 newMessageCount)`

#### State updates

- functionCall: 2024-01-01 16:18 UTC - now; currently used; address: [0xB6e0586616ebE79b2F86dDB32048c500D23b3AC3](https://etherscan.io/address/0xB6e0586616ebE79b2F86dDB32048c500D23b3AC3); selector: 0xa04cee60; signature: `function updateSendRoot(bytes32 root, bytes32 l2BlockHash) external`

## Milestones & Incidents

- 2024-04-10: [ArbOS v20 upgrade](https://forum.arbitrum.foundation/t/aip-arbos-version-20-atlas/20957). Introduces EIP-4844 data blobs for L1 data availability and Dencun-related opcodes on L2.
- 2024-01-05: [Parallel Mainnet closed launch](https://twitter.com/ParallelFi/status/1743048283684237574). Parallel Mainnet is open for developers.

## Risk summary

**Warning:** Fraud proof system is fully deployed but is not yet permissionless as it requires Validators to be whitelisted.

### Funds can be stolen if

1. a contract receives a malicious code upgrade. There is no delay on code upgrades (CRITICAL),
2. none of the whitelisted verifiers checks the published state. Fraud proofs assume at least one honest and able validator (CRITICAL).

### MEV can be extracted if

3. the operator exploits their centralized position and frontruns user transactions.

## Risk analysis

**Warning:** Critical contracts can be upgraded by an EOA which could result in the loss of all funds.

**Warning:** Fraud proof system is fully deployed but is not yet permissionless as it requires Validators to be whitelisted.

### Sequencer failure

Self sequence (2d delay; sentiment: good)

In the event of a sequencer failure, users can force transactions to be included in the project's chain by sending them to L1. There can be up to a 2d delay on this operation.

### State validation

Fraud proofs (INT) (6d challenge period; sentiment: bad)

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.

### Data availability

Onchain (sentiment: good)

All of the data needed for proof construction is published on Ethereum L1.

### Exit window

None (sentiment: bad)

There is no window for users to exit in case of an unwanted upgrade since contracts are instantly upgradable.

### Proposer failure

Self propose (12d 8h delay; sentiment: good)

Anyone can become a Proposer after 12d 8h of inactivity from the currently whitelisted Proposers.

## Stage

Parallel is not even a Stage 0 project.

**The project does not pass the walkaway test**: users are not able to exit in the presence of malicious operators if the Security Council disappears.

**Warning:** The requirement for available node software is under review

### Stage 0

1 issue needs fixing.

- Met: A complete and functional proof system is deployed.
- Met: The project calls itself a rollup.
- Met: State roots are posted to Ethereum L1.
- Met: Inputs for the state transition function are posted to Ethereum L1.
- Under review: A source-available node exists that can recreate the state from Ethereum L1 data. Please note that the ETHBEAT team has not verified the validity of the node source code.
- Issue: Fraud proof submission is not sufficiently decentralized.

### Stage 1

3 issues need fixing.

**Principle**

- Issue: Compromising ≥75% of the Security Council should be the only way (other than bugs) for a rollup to indefinitely block an L2→L1 message (e.g. a withdrawal) or push an invalid L2→L1 message (e.g. an invalid withdrawal) with a <7d exit window.

**Guidelines**

- Met: Users are able to exit without the help of the permissioned operators.
- Issue: 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.
- Issue: The Security Council is not properly set up.

### Stage 2

3 issues need fixing.

- Issue: Fraud proof submission is open only to whitelisted actors.
- Issue: Upgrades unrelated to onchain provable bugs provide less than 30d to exit.
- Issue: The Security Council's actions are not confined to onchain provable bugs.

[Learn more about Stages](https://ethbeat.org/stages).

Please keep in mind that these stages do not reflect project security, this is an opinionated assessment of project maturity based on subjective criteria, created with a goal of incentivizing projects to push toward better decentralization. Each team may have taken different paths to achieve this goal.

## Data availability

### 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.

**References**

- [Sequencing followed by deterministic execution - Arbitrum documentation](https://developer.offchainlabs.com/inside-arbitrum-nitro/#sequencing-followed-by-deterministic-execution)
- [SequencerInbox.sol - source code, addSequencerL2BatchFromOrigin function](https://etherscan.io/address/0x958985cf2c54f99ba4a599221A8090C1F9Cee9A5#code)

Learn more about the DA layer here: [Ethereum](https://ethbeat.org/projects/ethereum)

## State validation

![A diagram of the state validation](https://ethbeat.org/static/images/state-validation/orbit.b691a319.png)

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.

### State root proposals

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.

**Risks**

- 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).

**References**

- [How is fraud proven - Arbitrum documentation FAQ](https://docs.arbitrum.io/get-started/arbitrum-introduction)

### Challenges

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](https://medium.com/l2beat/fraud-proof-wars-b0cb4d0f452a). Since each challenge lasts 6d, this implies that the protocol can be subject to [delay attacks](https://medium.com/offchainlabs/solutions-to-delay-attacks-on-rollups-434f9d05a07a), 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.

**References**

- [Fraud Proof Wars: Arbitrum Classic](https://medium.com/l2beat/fraud-proof-wars-b0cb4d0f452a)

### Program Hashes

#### ArbOS wasmModuleRoot v31

A commitment to the exact WASM binary version used for Orbit stack optimistic dispute games.

- Hash: `0x260f5fa5c3176a856893642e149cf128b5a8de9f828afec8d11184415dd8dc69`
- Repository: https://github.com/OffchainLabs/nitro/tree/consensus-v31/arbos
- Verification: not verified
- Used in: [Parallel](https://ethbeat.org/layer2s/projects/parallel)

## Upgrades & Governance

### Past upgrades

The metrics include upgrades on the currently used proxy contracts. Historical proxy contracts and changes of such are not included.

- Count of upgrades: 5
- Last upgrade: 1y 7mo ago
- Avg upgrade interval: 1y

- 2025-03-30 02:36 UTC, upgrade of [Bridge](https://etherscan.io/address/0x5a961c7D162195a9Dc5a357Cc168b0694283382E#code): transaction [0x41c445bc5da5e4a440aeab5914ef6154a1a8e761336500e51868ca7595a99381](https://etherscan.io/tx/0x41c445bc5da5e4a440aeab5914ef6154a1a8e761336500e51868ca7595a99381), implementations: [0xC03cF2ec47426C2318F91496316c62e5FAf413f3](https://etherscan.io/address/0xC03cF2ec47426C2318F91496316c62e5FAf413f3#code) ([diff](https://disco.ethbeat.org/diff/eth:0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F/eth:0xC03cF2ec47426C2318F91496316c62e5FAf413f3))
- 2025-03-30 02:36 UTC, upgrade of [Bridge](https://etherscan.io/address/0x5a961c7D162195a9Dc5a357Cc168b0694283382E#code): transaction [0x41c445bc5da5e4a440aeab5914ef6154a1a8e761336500e51868ca7595a99381](https://etherscan.io/tx/0x41c445bc5da5e4a440aeab5914ef6154a1a8e761336500e51868ca7595a99381), implementations: [0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F](https://etherscan.io/address/0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F#code) ([diff](https://disco.ethbeat.org/diff/eth:0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F/eth:0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F))
- 2024-05-01 19:48 UTC, upgrade of [SequencerInbox](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8#code): transaction [0x2f5db148c87e87a1670b52d003d051efecdfb606bc0b265f36d7bfeb9977601e](https://etherscan.io/tx/0x2f5db148c87e87a1670b52d003d051efecdfb606bc0b265f36d7bfeb9977601e), implementations: [0x958985cf2c54f99ba4a599221A8090C1F9Cee9A5](https://etherscan.io/address/0x958985cf2c54f99ba4a599221A8090C1F9Cee9A5#code) ([diff](https://disco.ethbeat.org/diff/eth:0x383f16fB2809a56fC639c1eE2c93Ad2aa7Ee130A/eth:0x958985cf2c54f99ba4a599221A8090C1F9Cee9A5))
- 2024-04-10 17:26 UTC, upgrade of [SequencerInbox](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8#code): transaction [0xaa0434ce70e52e72a359fc871e5285e8504dc1e24c28b3882f85c603465e88ff](https://etherscan.io/tx/0xaa0434ce70e52e72a359fc871e5285e8504dc1e24c28b3882f85c603465e88ff), implementations: [0x383f16fB2809a56fC639c1eE2c93Ad2aa7Ee130A](https://etherscan.io/address/0x383f16fB2809a56fC639c1eE2c93Ad2aa7Ee130A#code) ([diff](https://disco.ethbeat.org/diff/eth:0x873484Ba63353C8b71210ce123B465512d408B27/eth:0x383f16fB2809a56fC639c1eE2c93Ad2aa7Ee130A))
- 2024-04-10 17:26 UTC, upgrade of [ChallengeManager](https://etherscan.io/address/0x28c32059d7e6147cf5257DFC127f7258beA1cdf4#code): transaction [0xaa0434ce70e52e72a359fc871e5285e8504dc1e24c28b3882f85c603465e88ff](https://etherscan.io/tx/0xaa0434ce70e52e72a359fc871e5285e8504dc1e24c28b3882f85c603465e88ff), implementations: [0x1D901DD7A5eFE421C3C437B147040E5AF22E6A43](https://etherscan.io/address/0x1D901DD7A5eFE421C3C437B147040E5AF22E6A43#code) ([diff](https://disco.ethbeat.org/diff/eth:0xEe9E5546A11Cb5b4A86e92DA05f2ef75C26E4754/eth:0x1D901DD7A5eFE421C3C437B147040E5AF22E6A43))
- 2024-01-01 16:35 UTC, deployment of [ERC20Gateway](https://etherscan.io/address/0x6Eb9240d4add111D5Fc81b10Ff12eECabcf9752d#code): transaction [0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4](https://etherscan.io/tx/0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4), implementations: [0xf43bce5D32742FFC862eA182b0b5544CbDBB0F02](https://etherscan.io/address/0xf43bce5D32742FFC862eA182b0b5544CbDBB0F02#code)
- 2024-01-01 16:35 UTC, deployment of [GatewayRouter](https://etherscan.io/address/0x5D657b905275F36AD62C3d5C36966975613aFB96#code): transaction [0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4](https://etherscan.io/tx/0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4), implementations: [0x6525137BfF366fbc0A89E3e5A4d244B5A0090a6D](https://etherscan.io/address/0x6525137BfF366fbc0A89E3e5A4d244B5A0090a6D#code)
- 2024-01-01 16:35 UTC, deployment of [CustomGateway](https://etherscan.io/address/0xa1c86E2362dba0525075622af6d5f739B1304D45#code): transaction [0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4](https://etherscan.io/tx/0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4), implementations: [0xedB05ED1a37750833fBE85b808c872D841d00859](https://etherscan.io/address/0xedB05ED1a37750833fBE85b808c872D841d00859#code)
- 2024-01-01 16:35 UTC, deployment of [L1WethGateway](https://etherscan.io/address/0x150286BdbE7C8Cd23D41a8e1e64438e0dc04dc3d#code): transaction [0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4](https://etherscan.io/tx/0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4), implementations: [0xa86996bED19547f7dEf22a087dD61b5F9Fb6C684](https://etherscan.io/address/0xa86996bED19547f7dEf22a087dD61b5F9Fb6C684#code)
- 2024-01-01 16:18 UTC, deployment of [Bridge](https://etherscan.io/address/0x5a961c7D162195a9Dc5a357Cc168b0694283382E#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F](https://etherscan.io/address/0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F#code)
- 2024-01-01 16:18 UTC, deployment of [SequencerInbox](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x873484Ba63353C8b71210ce123B465512d408B27](https://etherscan.io/address/0x873484Ba63353C8b71210ce123B465512d408B27#code)
- 2024-01-01 16:18 UTC, deployment of [ChallengeManager](https://etherscan.io/address/0x28c32059d7e6147cf5257DFC127f7258beA1cdf4#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0xEe9E5546A11Cb5b4A86e92DA05f2ef75C26E4754](https://etherscan.io/address/0xEe9E5546A11Cb5b4A86e92DA05f2ef75C26E4754#code)
- 2024-01-01 16:18 UTC, deployment of [RollupProxy](https://etherscan.io/address/0x6594085ca55a2B3a5fAD1C57A270D060eEa99877#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x0aE4dD666748bF0F6dB5c149Eab1D8aD27820A6A](https://etherscan.io/address/0x0aE4dD666748bF0F6dB5c149Eab1D8aD27820A6A#code), [0x660ea1675F7323dC3Ba0c8dDFB593225Eb01E3C1](https://etherscan.io/address/0x660ea1675F7323dC3Ba0c8dDFB593225Eb01E3C1#code)
- 2024-01-01 16:18 UTC, deployment of [UpgradeExecutor](https://etherscan.io/address/0xD368b8dC5cB6fA26A53b7588db9A87E509A72d89#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x6c21303F5986180B1394d2C89f3e883890E2867b](https://etherscan.io/address/0x6c21303F5986180B1394d2C89f3e883890E2867b#code)
- 2024-01-01 16:18 UTC, deployment of [Inbox](https://etherscan.io/address/0x12485B9d469c1D51d05b5C39e009D50eF0170cF7#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x1162084C3C6575121146582Db5BE43189e8CEe6b](https://etherscan.io/address/0x1162084C3C6575121146582Db5BE43189e8CEe6b#code)
- 2024-01-01 16:18 UTC, deployment of [Outbox](https://etherscan.io/address/0xB6e0586616ebE79b2F86dDB32048c500D23b3AC3#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x2a6DD4433ffa96dc1755814FC0d9cc83A5F68DeC](https://etherscan.io/address/0x2a6DD4433ffa96dc1755814FC0d9cc83A5F68DeC#code)
- 2024-01-01 16:18 UTC, deployment of [RollupEventInbox](https://etherscan.io/address/0x36E5DE57f862cf5bA28624845faB8c2fF6Aa41d2#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x13BE515E44Eefaf3eBEFAD684F1FBB574Ac0A494](https://etherscan.io/address/0x13BE515E44Eefaf3eBEFAD684F1FBB574Ac0A494#code)

## Updates

Each date links the update on the HTML page, which also shows its contract diffs.

### [2025-07-14 12:45 UTC](https://ethbeat.org/layer2s/projects/parallel?update=fa02bd14) (20 changes)

Discovery rerun on the same block number with only config-related changes.

### [2025-05-06 15:57 UTC](https://ethbeat.org/layer2s/projects/parallel?update=f41018d0) (6 changes)

ms signer change.

### [2025-05-02 17:24 UTC](https://ethbeat.org/layer2s/projects/parallel?update=fd80b057) (2 changes)

MS signer change.

### [2025-03-31 10:23 UTC](https://ethbeat.org/layer2s/projects/parallel?update=62b570f9) (5 changes)

[Double upgrade of the bridge](https://app.blocksec.com/explorer/tx/eth/0x41c445bc5da5e4a440aeab5914ef6154a1a8e761336500e51868ca7595a99381) with 26 ETH profit. Parallel is inactive/closed (see L2BEAT page).

### [2025-03-12 08:49 UTC](https://ethbeat.org/layer2s/projects/parallel?update=4713a8cd) (3 changes)

MS signer change.

### [2024-09-09 07:12 UTC](https://ethbeat.org/layer2s/projects/parallel?update=2710bc5b) (1 change)

Parallel had a 11d gap between batches delivered to the SequencerInbox. The sequencer-only window was 2d, so `forceInclusion()` should have been possible. (nobody used it)

The proposer was active and has a much longer max inactivity before allowing self-proposing (~12d).

Paradex is currently using the ArbOS 31 wasmmoduleroot but not the new ChallengeManager nor the OSP contracts seen in Arbitrum.

### [2024-09-02 06:58 UTC](https://ethbeat.org/layer2s/projects/parallel?update=c12ad740) (1 change)

One of the two (!) upgrade admin EOA's is removed.

### [2024-08-16 08:25 UTC](https://ethbeat.org/layer2s/projects/parallel?update=eec5186d) (4 changes)

The futureBlocks value enforces a max block height that a batch can be posted relative to the current block (likewise with futureSeconds). A small value for future blocks means that a relatively small L1 reorg can cause an otherwise valid batch to revert. They increased is to 96, or three epochs. The futureSeconds value is set to correspond to the new futureBlocks value. The delay is also changed - it's the delay time between tx submission and ability to do force inclusion on the L1. Compared to Arbitrum One all of the delays are higher here.

### [2024-08-12 07:44 UTC](https://ethbeat.org/layer2s/projects/parallel?update=b982c33c) (1 change)

Parallel is posting blobs again, for some reason they switched to calldata a while ago but they are back to blobs now.

### [2024-08-07 07:16 UTC](https://ethbeat.org/layer2s/projects/parallel?update=e0533329) (2 changes)

New batch poster address is added.

### [2024-08-06 11:35 UTC](https://ethbeat.org/layer2s/projects/parallel?update=a01a854f) (12 changes)

Conduit multisig is removed from permissions and replaced by an EOA. The single validator is replaced.
There is one batch posted with calldata and the Sequencer only window is increased and then reset again to the old value. (`maxTimeVariation.delaySeconds`)
The wasmModuleRoot is changed to the ArbOS 31 root. ([compare Nitro GH repo](https://github.com/OffchainLabs/nitro/blob/7defbd2f59ffc53229eddaa5d6588e1a81ed90ff/Dockerfile#L220))

### [2024-08-04 09:55 UTC](https://ethbeat.org/layer2s/projects/parallel?update=a526628b) (2 changes)

A second Multisig is added as UpgradeExecutor.
Furthermore, the UpgradeExecutor was EOA-governed since Jan 2024 by `0xefCf0c8faFB425997870f845e26fC6cA6EE6dD5C`.

### [2024-05-22 20:11 UTC](https://ethbeat.org/layer2s/projects/parallel?update=5c71c2bd) (9 changes)

ConduitMultisig update.

### [2024-05-02 08:17 UTC](https://ethbeat.org/layer2s/projects/parallel?update=1237da28) (high severity, 3 changes)

The implementation of SequencerInbox was upgraded to a different contract with identical code.
This was done to change the immutable boolean `isUsingFeeToken` to false. This immutable should indeed be false on ethereum mainnet as it signifies the base L1 using a custom fee token. (Used as a check for `submitBatchSpendingReport()` function that is needed for fee sequencer fee reimbursement)

### [2024-04-11 06:24 UTC](https://ethbeat.org/layer2s/projects/parallel?update=09a61d96) (high severity, 25 changes)

#### New deploys

OneStepProofEntry, OneStepProverHostIo, OneStepProverMath, OneStepProver0, OneStepProverMemory are redeployed and Reader4844 is added to be compatible with EIP-4844.

- OneStepProverHostIo: Compatibility with EIP-4844, most updates are KZG-related in function `executeReadPreImage()`; new function `modExp256()`
- Reader4844.sol: New unverified contract with the functions `getBlobBaseFee()`, `getDataHashes()` for reading blob data (hashes) (info from its interface)

#### SequencerInbox

In general most updates are EIP-4844 related, also the new role `batchPosterManager` is added and there are new checks regarding native tokens.

- Batch data flag-based decoding refined for blobs: `DATA_AUTHENTICATED_FLAG`, `BROTLI_MESSAGE_HEADER_FLAG`, `DAS_MESSAGE_HEADER_FLAG`, `DATA_BLOB_HEADER_FLAG`, `TREE_DAS_MESSAGE_HEADER_FLAG`, `ZERO_HEAVY_MESSAGE_HEADER_FLAG`
- new `batchPosterManager` functions and role: Can change the Sequencer addresses. (allows key rotation of batch posters)
- new `addSequencerL2BatchFromOrigin()` (with added `prevMessageCount, newMessageCount` in sig, old signature without them is now deprecated), `addSequencerL2BatchFromBlobs()`
- Gas refunds fetch blob price from Reader4844
- Rollup owner can update rollup address
- SequencerInbox contructor reverts if host chain is Arbitrum because blobs are not supported there
  - Checks for fee token usage and reverts if the native token is not ETH
- `forceInclusion()` now does not change the sequencer message count
- IBridge interface is introduced to use the vars TimeBounds and BatchDataLocation
- Hashing functions for blobs vs. calldata
- Time variation boundaries for batch posting vs. force inclusion -> format change

#### Changed wasmModuleRoot

Upgrade L2 system to [ArbOS Version 20 "Atlas"](https://forum.arbitrum.foundation/t/aip-arbos-version-20-atlas/20957)

### [2024-01-24 08:06 UTC](https://ethbeat.org/layer2s/projects/parallel?update=43a44049) (8 changes)

Contracts have been verified.

### [2024-01-08 13:05 UTC](https://ethbeat.org/layer2s/projects/parallel?update=731cf653) (22 changes)

Update discovery to include the multisig threshold.

## Operator

### 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.

**Risks**

- MEV can be extracted if the operator exploits their centralized position and frontruns user transactions.

**References**

- [Sequencer - Arbitrum documentation](https://docs.arbitrum.io/how-arbitrum-works/inside-arbitrum-nitro#the-sequencer)

### 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 2d 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.

**References**

- [SequencerInbox.sol - source code, forceInclusion function](https://etherscan.io/address/0x958985cf2c54f99ba4a599221A8090C1F9Cee9A5#code)
- [Sequencer Isn't Doing Its Job - Arbitrum documentation](https://docs.arbitrum.io/how-arbitrum-works/sequencer#unhappyuncommon-case-sequencer-isnt-doing-its-job)

## Sequencing

### 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 2d.

## Withdrawals

### Regular messaging

The user initiates L2->L1 messages by submitting a regular transaction on this chain. When the block containing that transaction is settled, the message becomes available for processing on L1. The process of block finalization usually takes several days to complete.

**References**

- [Transaction lifecycle - Arbitrum documentation](https://developer.offchainlabs.com/tx-lifecycle)
- [L2 to L1 Messages - Arbitrum documentation](https://docs.arbitrum.io/how-arbitrum-works/deep-dives/l2-to-l1-messaging)
- [Mainnet for everyone - Arbitrum Blog](https://offchain.medium.com/mainnet-for-everyone-27ce0f67c85e)

### 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.

## Other considerations

### EVM compatible smart contracts are supported

Arbitrum One uses Nitro technology that allows running fraud proofs by executing EVM code on top of WASM.

**References**

- [Inside Arbitrum Nitro](https://developer.offchainlabs.com/inside-arbitrum-nitro/)

## Permissions

Explore these contracts and permissions in Disco, ETHBEAT's contract explorer: https://disco.ethbeat.org/ui/p/parallel

### Ethereum

#### Actors

##### ParallelMultisig

Addresses: [0x19293FBec52F94165f903708a74513Dd6dFedd0a](https://etherscan.io/address/0x19293FBec52F94165f903708a74513Dd6dFedd0a)

A Multisig with 3/3 threshold.
- Can upgrade **with no delay**
  - Inbox [via: UpgradeExecutor → ProxyAdmin]
  - L1WethGateway [via: UpgradeExecutor → ProxyAdmin]
  - ChallengeManager [via: UpgradeExecutor → ProxyAdmin]
  - RollupEventInbox [via: UpgradeExecutor → ProxyAdmin]
  - Bridge [via: UpgradeExecutor → ProxyAdmin]
  - GatewayRouter [via: UpgradeExecutor → ProxyAdmin]
  - RollupProxy [via: UpgradeExecutor]
  - ERC20Gateway [via: UpgradeExecutor → ProxyAdmin]
  - CustomGateway [via: UpgradeExecutor → ProxyAdmin]
  - SequencerInbox [via: UpgradeExecutor → ProxyAdmin]
  - Outbox [via: UpgradeExecutor → ProxyAdmin]
  - UpgradeExecutor [via: UpgradeExecutor → ProxyAdmin]
- Can 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 and DACs, set the Sequencer-only window, introduce an allowList to the bridge and whitelist Inboxes/Outboxes [via: UpgradeExecutor]

Participants (3): [0x13E83b0423534Eb6D542237F590096CEE5077056](https://etherscan.io/address/0x13E83b0423534Eb6D542237F590096CEE5077056), [0x3968de97416c875F50FFC60A4A4E84378bF16Ad5](https://etherscan.io/address/0x3968de97416c875F50FFC60A4A4E84378bF16Ad5), [0x909e36B512Ed45250fdff513523119d825647695](https://etherscan.io/address/0x909e36B512Ed45250fdff513523119d825647695)

##### EOA 1

Addresses: [0xefCf0c8faFB425997870f845e26fC6cA6EE6dD5C](https://etherscan.io/address/0xefCf0c8faFB425997870f845e26fC6cA6EE6dD5C)

- Can upgrade **with no delay**
  - Inbox [via: UpgradeExecutor → ProxyAdmin]
  - L1WethGateway [via: UpgradeExecutor → ProxyAdmin]
  - ChallengeManager [via: UpgradeExecutor → ProxyAdmin]
  - RollupEventInbox [via: UpgradeExecutor → ProxyAdmin]
  - Bridge [via: UpgradeExecutor → ProxyAdmin]
  - GatewayRouter [via: UpgradeExecutor → ProxyAdmin]
  - RollupProxy [via: UpgradeExecutor]
  - ERC20Gateway [via: UpgradeExecutor → ProxyAdmin]
  - CustomGateway [via: UpgradeExecutor → ProxyAdmin]
  - SequencerInbox [via: UpgradeExecutor → ProxyAdmin]
  - Outbox [via: UpgradeExecutor → ProxyAdmin]
  - UpgradeExecutor [via: UpgradeExecutor → ProxyAdmin]
- Can 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 and DACs, set the Sequencer-only window, introduce an allowList to the bridge and whitelist Inboxes/Outboxes [via: UpgradeExecutor]

##### 2 EOAs

Addresses: [0x40acDc94a00b33151B40763b3Fed7C46fF639Df4](https://etherscan.io/address/0x40acDc94a00b33151B40763b3Fed7C46fF639Df4) (EOA 2), [0x7a6BD06483710252d807bE205255E69490efca3A](https://etherscan.io/address/0x7a6BD06483710252d807bE205255E69490efca3A) (EOA 3)

- Can interact with SequencerInbox
  - Can submit transaction batches or commitments to the SequencerInbox contract on the host chain

##### EOA 4

Addresses: [0xcCE420Beb5a68091572A1cd860e10aE3Ce286FeA](https://etherscan.io/address/0xcCE420Beb5a68091572A1cd860e10aE3Ce286FeA)

- Can interact with RollupProxy
  - Can propose new state roots (called nodes) and challenge state roots on the host chain

## Smart contracts

![A diagram of the smart contract architecture](https://ethbeat.org/static/images/architecture/orbit-rollup.7634b065.png)

Explore these contracts and permissions in Disco, ETHBEAT's contract explorer: https://disco.ethbeat.org/ui/p/parallel

### Ethereum

#### ChallengeManager

Addresses: [0x28c32059d7e6147cf5257DFC127f7258beA1cdf4](https://etherscan.io/address/0x28c32059d7e6147cf5257DFC127f7258beA1cdf4#code), [0x1D901DD7A5eFE421C3C437B147040E5AF22E6A43](https://etherscan.io/address/0x1D901DD7A5eFE421C3C437B147040E5AF22E6A43#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: 1, Last upgrade: 2y 6mo ago, Avg upgrade interval: 1y 5mo)

- 2024-04-10 17:26 UTC, upgrade of [ChallengeManager](https://etherscan.io/address/0x28c32059d7e6147cf5257DFC127f7258beA1cdf4#code): transaction [0xaa0434ce70e52e72a359fc871e5285e8504dc1e24c28b3882f85c603465e88ff](https://etherscan.io/tx/0xaa0434ce70e52e72a359fc871e5285e8504dc1e24c28b3882f85c603465e88ff), implementations: [0x1D901DD7A5eFE421C3C437B147040E5AF22E6A43](https://etherscan.io/address/0x1D901DD7A5eFE421C3C437B147040E5AF22E6A43#code) ([diff](https://disco.ethbeat.org/diff/eth:0xEe9E5546A11Cb5b4A86e92DA05f2ef75C26E4754/eth:0x1D901DD7A5eFE421C3C437B147040E5AF22E6A43))
- 2024-01-01 16:18 UTC, deployment of [ChallengeManager](https://etherscan.io/address/0x28c32059d7e6147cf5257DFC127f7258beA1cdf4#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0xEe9E5546A11Cb5b4A86e92DA05f2ef75C26E4754](https://etherscan.io/address/0xEe9E5546A11Cb5b4A86e92DA05f2ef75C26E4754#code)

Contract that allows challenging state roots. Can be called through the RollupProxy by Validators or the UpgradeExecutor.
- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

#### Bridge (escrow)

Addresses: [0x5a961c7D162195a9Dc5a357Cc168b0694283382E](https://etherscan.io/address/0x5a961c7D162195a9Dc5a357Cc168b0694283382E#code), [0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F](https://etherscan.io/address/0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: 2, Last upgrade: 1y 7mo ago, Avg upgrade interval: 11mo 15d)

- 2025-03-30 02:36 UTC, upgrade of [Bridge](https://etherscan.io/address/0x5a961c7D162195a9Dc5a357Cc168b0694283382E#code): transaction [0x41c445bc5da5e4a440aeab5914ef6154a1a8e761336500e51868ca7595a99381](https://etherscan.io/tx/0x41c445bc5da5e4a440aeab5914ef6154a1a8e761336500e51868ca7595a99381), implementations: [0xC03cF2ec47426C2318F91496316c62e5FAf413f3](https://etherscan.io/address/0xC03cF2ec47426C2318F91496316c62e5FAf413f3#code) ([diff](https://disco.ethbeat.org/diff/eth:0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F/eth:0xC03cF2ec47426C2318F91496316c62e5FAf413f3))
- 2025-03-30 02:36 UTC, upgrade of [Bridge](https://etherscan.io/address/0x5a961c7D162195a9Dc5a357Cc168b0694283382E#code): transaction [0x41c445bc5da5e4a440aeab5914ef6154a1a8e761336500e51868ca7595a99381](https://etherscan.io/tx/0x41c445bc5da5e4a440aeab5914ef6154a1a8e761336500e51868ca7595a99381), implementations: [0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F](https://etherscan.io/address/0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F#code) ([diff](https://disco.ethbeat.org/diff/eth:0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F/eth:0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F))
- 2024-01-01 16:18 UTC, deployment of [Bridge](https://etherscan.io/address/0x5a961c7D162195a9Dc5a357Cc168b0694283382E#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F](https://etherscan.io/address/0x1c6ACCd9d66f3B993928E7439c9A2d67b94a445F#code)

Escrow contract for the project's gas token (can be different from ETH). Keeps a list of allowed Inboxes and Outboxes for canonical bridge messaging.
- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig

The following tokens are included in the value secured calculation: ETH

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

Implementation used in: [AlienX](https://ethbeat.org/layer2s/projects/alienx#Bridge)

#### RollupProxy

Addresses: [0x6594085ca55a2B3a5fAD1C57A270D060eEa99877](https://etherscan.io/address/0x6594085ca55a2B3a5fAD1C57A270D060eEa99877#code), [0x0aE4dD666748bF0F6dB5c149Eab1D8aD27820A6A](https://etherscan.io/address/0x0aE4dD666748bF0F6dB5c149Eab1D8aD27820A6A#code) (Implementation #1 (Upgradable)), [0x660ea1675F7323dC3Ba0c8dDFB593225Eb01E3C1](https://etherscan.io/address/0x660ea1675F7323dC3Ba0c8dDFB593225Eb01E3C1#code) (Implementation #2 (Upgradable)), [0xD368b8dC5cB6fA26A53b7588db9A87E509A72d89](https://etherscan.io/address/0xD368b8dC5cB6fA26A53b7588db9A87E509A72d89#code) (Admin)

**Past upgrades** (Count of upgrades: No upgrades, Last upgrade: N/A, Avg upgrade interval: N/A)

- 2024-01-01 16:18 UTC, deployment of [RollupProxy](https://etherscan.io/address/0x6594085ca55a2B3a5fAD1C57A270D060eEa99877#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x0aE4dD666748bF0F6dB5c149Eab1D8aD27820A6A](https://etherscan.io/address/0x0aE4dD666748bF0F6dB5c149Eab1D8aD27820A6A#code), [0x660ea1675F7323dC3Ba0c8dDFB593225Eb01E3C1](https://etherscan.io/address/0x660ea1675F7323dC3Ba0c8dDFB593225Eb01E3C1#code)

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).
- Roles:
  - **admin**: UpgradeExecutor; ultimately EOA 1, ParallelMultisig
  - **owner**: UpgradeExecutor; ultimately EOA 1, ParallelMultisig
  - **validators**: EOA 4

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

#### SequencerInbox

Addresses: [0xb4795A0edae98d7820C37F06f6b858e7acb51DF8](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8#code), [0x958985cf2c54f99ba4a599221A8090C1F9Cee9A5](https://etherscan.io/address/0x958985cf2c54f99ba4a599221A8090C1F9Cee9A5#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: 2, Last upgrade: 2y 6mo ago, Avg upgrade interval: 11mo 15d)

- 2024-05-01 19:48 UTC, upgrade of [SequencerInbox](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8#code): transaction [0x2f5db148c87e87a1670b52d003d051efecdfb606bc0b265f36d7bfeb9977601e](https://etherscan.io/tx/0x2f5db148c87e87a1670b52d003d051efecdfb606bc0b265f36d7bfeb9977601e), implementations: [0x958985cf2c54f99ba4a599221A8090C1F9Cee9A5](https://etherscan.io/address/0x958985cf2c54f99ba4a599221A8090C1F9Cee9A5#code) ([diff](https://disco.ethbeat.org/diff/eth:0x383f16fB2809a56fC639c1eE2c93Ad2aa7Ee130A/eth:0x958985cf2c54f99ba4a599221A8090C1F9Cee9A5))
- 2024-04-10 17:26 UTC, upgrade of [SequencerInbox](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8#code): transaction [0xaa0434ce70e52e72a359fc871e5285e8504dc1e24c28b3882f85c603465e88ff](https://etherscan.io/tx/0xaa0434ce70e52e72a359fc871e5285e8504dc1e24c28b3882f85c603465e88ff), implementations: [0x383f16fB2809a56fC639c1eE2c93Ad2aa7Ee130A](https://etherscan.io/address/0x383f16fB2809a56fC639c1eE2c93Ad2aa7Ee130A#code) ([diff](https://disco.ethbeat.org/diff/eth:0x873484Ba63353C8b71210ce123B465512d408B27/eth:0x383f16fB2809a56fC639c1eE2c93Ad2aa7Ee130A))
- 2024-01-01 16:18 UTC, deployment of [SequencerInbox](https://etherscan.io/address/0xb4795A0edae98d7820C37F06f6b858e7acb51DF8#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x873484Ba63353C8b71210ce123B465512d408B27](https://etherscan.io/address/0x873484Ba63353C8b71210ce123B465512d408B27#code)

A sequencer (registered in this contract) can submit transaction batches or commitments here.
- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig
  - **batchPosters**: EOA 2, EOA 3

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

#### UpgradeExecutor

Addresses: [0xD368b8dC5cB6fA26A53b7588db9A87E509A72d89](https://etherscan.io/address/0xD368b8dC5cB6fA26A53b7588db9A87E509A72d89#code), [0x6c21303F5986180B1394d2C89f3e883890E2867b](https://etherscan.io/address/0x6c21303F5986180B1394d2C89f3e883890E2867b#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: No upgrades, Last upgrade: N/A, Avg upgrade interval: N/A)

- 2024-01-01 16:18 UTC, deployment of [UpgradeExecutor](https://etherscan.io/address/0xD368b8dC5cB6fA26A53b7588db9A87E509A72d89#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x6c21303F5986180B1394d2C89f3e883890E2867b](https://etherscan.io/address/0x6c21303F5986180B1394d2C89f3e883890E2867b#code)

Central contract defining the access control permissions for upgrading the system contract implementations.
- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig
  - **executors**: EOA 1, ParallelMultisig

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

Implementation used in: [AlienX](https://ethbeat.org/layer2s/projects/alienx#UpgradeExecutor), [Gravity](https://ethbeat.org/layer2s/projects/galxegravity#UpgradeExecutor), [Reya](https://ethbeat.org/layer2s/projects/reya#UpgradeExecutor), [SX Network](https://ethbeat.org/layer2s/projects/sxnetwork#UpgradeExecutor)

#### Inbox

Addresses: [0x12485B9d469c1D51d05b5C39e009D50eF0170cF7](https://etherscan.io/address/0x12485B9d469c1D51d05b5C39e009D50eF0170cF7#code), [0x1162084C3C6575121146582Db5BE43189e8CEe6b](https://etherscan.io/address/0x1162084C3C6575121146582Db5BE43189e8CEe6b#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: No upgrades, Last upgrade: N/A, Avg upgrade interval: N/A)

- 2024-01-01 16:18 UTC, deployment of [Inbox](https://etherscan.io/address/0x12485B9d469c1D51d05b5C39e009D50eF0170cF7#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x1162084C3C6575121146582Db5BE43189e8CEe6b](https://etherscan.io/address/0x1162084C3C6575121146582Db5BE43189e8CEe6b#code)

Facilitates sending L1 to L2 messages like depositing ETH, but does not escrow funds.
- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

#### ERC20Gateway (escrow)

Addresses: [0x6Eb9240d4add111D5Fc81b10Ff12eECabcf9752d](https://etherscan.io/address/0x6Eb9240d4add111D5Fc81b10Ff12eECabcf9752d#code), [0xf43bce5D32742FFC862eA182b0b5544CbDBB0F02](https://etherscan.io/address/0xf43bce5D32742FFC862eA182b0b5544CbDBB0F02#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: No upgrades, Last upgrade: N/A, Avg upgrade interval: N/A)

- 2024-01-01 16:35 UTC, deployment of [ERC20Gateway](https://etherscan.io/address/0x6Eb9240d4add111D5Fc81b10Ff12eECabcf9752d#code): transaction [0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4](https://etherscan.io/tx/0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4), implementations: [0xf43bce5D32742FFC862eA182b0b5544CbDBB0F02](https://etherscan.io/address/0xf43bce5D32742FFC862eA182b0b5544CbDBB0F02#code)

Escrows deposited ERC-20 assets for the canonical Bridge. Upon depositing, a generic token representation will be minted at the destination. Withdrawals are initiated by the Outbox contract.
- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig

All supported tokens in this escrow are included in the value secured calculation.

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

Implementation used in: [AlienX](https://ethbeat.org/layer2s/projects/alienx#ERC20Gateway), [Robinhood Chain](https://ethbeat.org/layer2s/projects/robinhood#L1ERC20Gateway)

#### Outbox

Addresses: [0xB6e0586616ebE79b2F86dDB32048c500D23b3AC3](https://etherscan.io/address/0xB6e0586616ebE79b2F86dDB32048c500D23b3AC3#code), [0x2a6DD4433ffa96dc1755814FC0d9cc83A5F68DeC](https://etherscan.io/address/0x2a6DD4433ffa96dc1755814FC0d9cc83A5F68DeC#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: No upgrades, Last upgrade: N/A, Avg upgrade interval: N/A)

- 2024-01-01 16:18 UTC, deployment of [Outbox](https://etherscan.io/address/0xB6e0586616ebE79b2F86dDB32048c500D23b3AC3#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x2a6DD4433ffa96dc1755814FC0d9cc83A5F68DeC](https://etherscan.io/address/0x2a6DD4433ffa96dc1755814FC0d9cc83A5F68DeC#code)

Facilitates L2 to L1 contract calls: Messages initiated from L2 (for example withdrawal messages) eventually resolve in execution on L1.
- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

Implementation used in: [AlienX](https://ethbeat.org/layer2s/projects/alienx#Outbox)

#### GatewayRouter

Addresses: [0x5D657b905275F36AD62C3d5C36966975613aFB96](https://etherscan.io/address/0x5D657b905275F36AD62C3d5C36966975613aFB96#code), [0x6525137BfF366fbc0A89E3e5A4d244B5A0090a6D](https://etherscan.io/address/0x6525137BfF366fbc0A89E3e5A4d244B5A0090a6D#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: No upgrades, Last upgrade: N/A, Avg upgrade interval: N/A)

- 2024-01-01 16:35 UTC, deployment of [GatewayRouter](https://etherscan.io/address/0x5D657b905275F36AD62C3d5C36966975613aFB96#code): transaction [0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4](https://etherscan.io/tx/0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4), implementations: [0x6525137BfF366fbc0A89E3e5A4d244B5A0090a6D](https://etherscan.io/address/0x6525137BfF366fbc0A89E3e5A4d244B5A0090a6D#code)

This routing contract maps tokens to the correct escrow (gateway) to be then bridged with canonical messaging.
- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

Implementation used in: [AlienX](https://ethbeat.org/layer2s/projects/alienx#GatewayRouter), [Robinhood Chain](https://ethbeat.org/layer2s/projects/robinhood#L1GatewayRouter)

#### CustomGateway (escrow)

Addresses: [0xa1c86E2362dba0525075622af6d5f739B1304D45](https://etherscan.io/address/0xa1c86E2362dba0525075622af6d5f739B1304D45#code), [0xedB05ED1a37750833fBE85b808c872D841d00859](https://etherscan.io/address/0xedB05ED1a37750833fBE85b808c872D841d00859#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: No upgrades, Last upgrade: N/A, Avg upgrade interval: N/A)

- 2024-01-01 16:35 UTC, deployment of [CustomGateway](https://etherscan.io/address/0xa1c86E2362dba0525075622af6d5f739B1304D45#code): transaction [0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4](https://etherscan.io/tx/0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4), implementations: [0xedB05ED1a37750833fBE85b808c872D841d00859](https://etherscan.io/address/0xedB05ED1a37750833fBE85b808c872D841d00859#code)

Escrows deposited assets for the canonical bridge that are externally governed or need custom token contracts with e.g. minting rights or upgradeability.
- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig

All supported tokens in this escrow are included in the value secured calculation.

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

#### L1WethGateway

Addresses: [0x150286BdbE7C8Cd23D41a8e1e64438e0dc04dc3d](https://etherscan.io/address/0x150286BdbE7C8Cd23D41a8e1e64438e0dc04dc3d#code), [0xa86996bED19547f7dEf22a087dD61b5F9Fb6C684](https://etherscan.io/address/0xa86996bED19547f7dEf22a087dD61b5F9Fb6C684#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: No upgrades, Last upgrade: N/A, Avg upgrade interval: N/A)

- 2024-01-01 16:35 UTC, deployment of [L1WethGateway](https://etherscan.io/address/0x150286BdbE7C8Cd23D41a8e1e64438e0dc04dc3d#code): transaction [0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4](https://etherscan.io/tx/0x13cbbc1a526c431bc86f883ba14816912d3f1a6f92105d2c34a08c15d806ffa4), implementations: [0xa86996bED19547f7dEf22a087dD61b5F9Fb6C684](https://etherscan.io/address/0xa86996bED19547f7dEf22a087dD61b5F9Fb6C684#code)

- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

Implementation used in: [Robinhood Chain](https://ethbeat.org/layer2s/projects/robinhood#L1WethGateway)

#### OneStepProverHostIo

Addresses: [0x17e7F68ce50A77e55C7834ddF31AEf86403B8010](https://etherscan.io/address/0x17e7F68ce50A77e55C7834ddF31AEf86403B8010#code)

One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.

#### ValidatorUtils

Addresses: [0x2b0E04Dc90e3fA58165CB41E2834B44A56E766aF](https://etherscan.io/address/0x2b0E04Dc90e3fA58165CB41E2834B44A56E766aF#code)

This contract implements view only utilities for validators.

Implementation used in: [AlienX](https://ethbeat.org/layer2s/projects/alienx#ValidatorUtils), [SX Network](https://ethbeat.org/layer2s/projects/sxnetwork#ValidatorUtils)

#### RollupEventInbox

Addresses: [0x36E5DE57f862cf5bA28624845faB8c2fF6Aa41d2](https://etherscan.io/address/0x36E5DE57f862cf5bA28624845faB8c2fF6Aa41d2#code), [0x13BE515E44Eefaf3eBEFAD684F1FBB574Ac0A494](https://etherscan.io/address/0x13BE515E44Eefaf3eBEFAD684F1FBB574Ac0A494#code) (Implementation (Upgradable)), [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code) (Admin)

**Past upgrades** (Count of upgrades: No upgrades, Last upgrade: N/A, Avg upgrade interval: N/A)

- 2024-01-01 16:18 UTC, deployment of [RollupEventInbox](https://etherscan.io/address/0x36E5DE57f862cf5bA28624845faB8c2fF6Aa41d2#code): transaction [0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df](https://etherscan.io/tx/0x56a0bbc36c0e79b2338cddce3f80c7998dd0f526d885a6b1aa827543769619df), implementations: [0x13BE515E44Eefaf3eBEFAD684F1FBB574Ac0A494](https://etherscan.io/address/0x13BE515E44Eefaf3eBEFAD684F1FBB574Ac0A494#code)

Helper contract sending configuration data over the bridge during the systems initialization.
- Roles:
  - **admin**: ProxyAdmin; ultimately EOA 1, ParallelMultisig

Can be upgraded by: ParallelMultisig with no delay, EOA 1 with no delay

Implementation used in: [AlienX](https://ethbeat.org/layer2s/projects/alienx#RollupEventInbox)

#### OneStepProofEntry

Addresses: [0x57EA090Ac0554d174AE0e2855B460e84A1A7C221](https://etherscan.io/address/0x57EA090Ac0554d174AE0e2855B460e84A1A7C221#code)

One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.

#### ProxyAdmin

Addresses: [0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d](https://etherscan.io/address/0x6d4bE7c1a618D43bE4a1Bd7F8eC8E079Ff52Fb4d#code)

- Roles:
  - **owner**: UpgradeExecutor

#### OneStepProver0

Addresses: [0x72B166070781a552D7b95a907eF59ca05d3D5a62](https://etherscan.io/address/0x72B166070781a552D7b95a907eF59ca05d3D5a62#code)

One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.

#### OneStepProverMemory

Addresses: [0x8b73Ef238ADaB31EBC7c05423d243c345241a22f](https://etherscan.io/address/0x8b73Ef238ADaB31EBC7c05423d243c345241a22f#code)

One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.

#### OneStepProverMath

Addresses: [0x90eC62De2EB7C7512a22bD2D55926AD6bA609F38](https://etherscan.io/address/0x90eC62De2EB7C7512a22bD2D55926AD6bA609F38#code)

One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.

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).

### Program Hashes

#### ArbOS wasmModuleRoot v31

A commitment to the exact WASM binary version used for Orbit stack optimistic dispute games.

- Hash: `0x260f5fa5c3176a856893642e149cf128b5a8de9f828afec8d11184415dd8dc69`
- Repository: https://github.com/OffchainLabs/nitro/tree/consensus-v31/arbos
- Verification: not verified
- Used in: [Parallel](https://ethbeat.org/layer2s/projects/parallel)