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Public Goods Network logoPublic Goods Network

This project is archived.
PGN was sunset in June 2024 and the centralized operator stopped their service. The current canonical bridge escrow contracts are modified to allow for withdrawals of ETH and ERC-20s based on a pre-configured merkle root.

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About

Public Goods Network is an OP stack chain focused on funding public goods.


Value Locked
$697.38 K11.1%
Canonically Bridged
$697.38 K
Externally Bridged
$0.00
Natively Minted
$0.00

  • Tokens
  • Daily UOPS
    0.000.00%
  • 30D ops count
    97.00

  • Type
    Optimium
  • Purpose
    Universal
  • Sequencer failureState validationData availabilityExit windowProposer failure

    Badges

    About

    Public Goods Network is an OP stack chain focused on funding public goods.


    Recategorisation

    179d
    05h
    54m
    42s

    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:

    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.

    There is no data availability bridge

    Consequence: projects without a data availability bridge fully rely on single entities (the sequencer) to honestly rely available data roots on Ethereum. A malicious sequencer can collude with the proposer to finalize an unavailable state, which can cause loss of funds.

    Learn more about the recategorisation here.

    Value Locked
    Canonical
    External
    Native
    Milestones & Incidents

    PGN unpauses the bridge

    2024 Dec 17th

    PGN unpauses the bridge after claiming contracts are updated.

    Learn more

    PGN starts sunset process

    2024 Dec 10th

    PGN starts its shutdown by pausing the bridge.

    Learn more
    Risk summary
    Risk analysis
    Sequencer failureState validationData availabilityExit windowProposer failure

    Sequencer failure

    Self sequence

    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 is a 12h delay on this operation.

    State validation

    None

    Currently the system permits invalid state roots. More details in project overview.

    Data availability

    External

    Proof construction and state derivation fully rely on data that is posted on Celestia. Sequencer tx roots are not checked against the Blobstream bridge data roots onchain, but L2 nodes can verify data availability by running a Celestia light client.

    Exit window

    None

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

    Proposer failure

    Cannot withdraw

    Only the whitelisted proposers can publish state roots on L1, so in the event of failure the withdrawals are frozen.

    Technology

    Fraud proofs are not enabled

    OP Stack projects can use the OP fault proof system, already being deployed on some. This project though is not using fault proofs yet and is relying on the honesty of the permissioned Proposer and Challengers to ensure state correctness. The smart contract system permits invalid state roots.

    • Funds can be stolen if an invalid state root is submitted to the system (CRITICAL).

    1. L2OutputOracle.sol - Etherscan source code, deleteL2Outputs function

    Data is posted to Celestia

    Transactions roots are posted onchain and the full data is posted on Celestia. Since the Blobstream bridge is not used, availability of the data is not verified against Celestia validators, meaning that the Sequencer can single-handedly publish unavailable roots.

    • 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).

    1. Introducing Blobstream: streaming modular DA to Ethereum
    2. Derivation: Batch submission - OP Mainnet specs
    3. BatchInbox - Etherscan address
    4. OptimismPortal.sol - Etherscan source code, depositTransaction function
    State derivation
    Node software

    The rollup node is composed of two software components: op-node, implementing consensus related logic, and op-geth, implementing execution logic. The configuration file can be found here.

    Compression scheme

    Data batches are compressed using the zlib algorithm with best compression level.

    Genesis state

    The genesis file can be found here.

    Data format

    The format specification of Sequencer’s data batches can be found here.

    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.

    1. L2OutputOracle.sol - Etherscan source code, CHALLENGER address
    2. L2OutputOracle.sol - Etherscan source code, PROPOSER address

    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.

    1. Sequencing Window - OP Mainnet Specs
    2. OptimismPortal.sol - Etherscan source code, depositTransaction function
    Withdrawals

    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 takes a challenge period of 7d 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).

    1. OptimismPortal.sol - Etherscan source code, proveWithdrawalTransaction function
    2. OptimismPortal.sol - Etherscan source code, finalizeWithdrawalTransaction function
    3. L2OutputOracle.sol - Etherscan source code, PROPOSER check

    Forced exit

    If the user experiences censorship from the operator with regular exit they can submit their withdrawal requests directly on L1. The system is then obliged to service this request or halt all withdrawals, including forced withdrawals from L1 and regular withdrawals initiated on L2. Once the force operation is submitted and if the request is serviced, the operation follows the flow of a regular exit.

    1. Forced withdrawal from an OP Stack blockchain
    Other considerations

    EVM compatible smart contracts are supported

    OP stack chains are 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 L2.

    1. Introducing EVM Equivalence
    Permissions

    The system uses the following set of permissioned addresses:

    Challenger PgnMultisig

    Challenger is an actor allowed to challenge or delete state roots proposed by a Proposer.

    Guardian PgnMultisig

    Guardian is an actor allowed to pause deposits and withdrawals.

    Proposer EOA 1

    Proposer is an actor allowed to post new state roots of the current layer to the host chain.

    Sequencer EOA 2

    Sequencer is an actor allowed to commit transactions from the current layer to the host chain.

    BalanceClaimer 0x0Ca4…BC21
    • Can change the configuration of OptimismPortal - withdraw ETH escrowed in the OptimismPortal.
    • Can change the configuration of L1StandardBridge - withdraw ERC-20 tokens escrowed in the bridge.
    • Allows proving ERC20 and/or ETH balances of L2 accounts with a merkle proof and without having to trigger a withdrawal transaction on the L2. The merkle root is immutable and set upon creation of this contract.
    PgnMultisig 0x39E1…5f84
    • A Gnosis Safe with 3 / 8 threshold.
    • A Challenger.
    • A Guardian.

    Those are the participants of the PgnMultisig.

    ConduitMultisig 0x4a49…A746
    • A Gnosis Safe with 4 / 8 threshold.
    • Can act on behalf of ProxyAdmin.
    • Can change the configuration of AddressManager (acting via ProxyAdmin) - set and change address mappings.
    • Can change the configuration of SystemConfig - it can update the preconfer address, the batch submitter (Sequencer) address and the gas configuration of the system.
    • Can upgrade the implementation of BalanceClaimer, SystemConfig, L2OutputOracle, OptimismPortal (acting via ProxyAdmin).
    • Can upgrade the implementation of L1StandardBridge (acting via ProxyAdmin) - upgrading the bridge implementation can give access to all funds escrowed therein.

    Used in:

    Those are the participants of the ConduitMultisig.

    Smart contracts
    A diagram of the smart contract architecture
    A diagram of the smart contract architecture

    The system consists of the following smart contracts on the host chain (Ethereum):

    AddressManager 0x09d5…AD3e

    Legacy contract used to manage a mapping of string names to addresses. Modern OP stack uses a different standard proxy system instead, but this contract is still necessary for backwards compatibility with several older contracts.

    Contains configuration parameters such as the Sequencer address, gas limit on this chain and the unsafe block signer address.

    Can be upgraded by:

    Upgrade delay: No delay

    Sends messages from host chain to this chain, and relays messages back onto host chain. In the event that a message sent from host chain to this chain is rejected for exceeding this chain’s epoch gas limit, it can be resubmitted via this contract’s replay function.

    Contains a list of proposed state roots which Proposers assert to be a result of block execution. Currently only the PROPOSER address can submit new state roots.

    Can be upgraded by:

    Upgrade delay: No delay

    The main entry point to deposit funds from host chain to this chain. It also allows to prove and finalize withdrawals. This contract stores the following tokens: ETH.

    Can be upgraded by:

    Upgrade delay: No delay

    ProxyAdmin 0xc6A8…4cc4
    • Can be used to configure AddressManager - set and change address mappings.
    • Can be used to upgrade implementation of BalanceClaimer, SystemConfig, L2OutputOracle, OptimismPortal.
    • Can be used to upgrade implementation of L1StandardBridge - upgrading the bridge implementation can give access to all funds escrowed therein.

    The main entry point to deposit ERC20 tokens from host chain to this chain. This contract can store any token. This contract can store any token.

    Can be upgraded by:

    Upgrade delay: No delay

    Value Locked is calculated based on these smart contracts and tokens:

    Main entry point for users depositing ERC20 token that do not require custom gateway.

    Can be upgraded by:

    Upgrade delay: No delay

    Main entry point for users depositing ETH.

    Can be upgraded by:

    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).

    Knowledge nuggets