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K2

K2 has been shut down. On 2026-09-15 the OptimismPortal and L1StandardBridge were upgraded to disable deposits and standard withdrawals: escrowed ETH and ERC20s can only be claimed on L1Layer 1 (L1) is a blockchain that is self-reliant on its validator set for its security and consensus properties. Ethereum is an example of a layer 1. Blockchains started receiving the moniker of layer 1 once layer 2 became a meaningful area of development. with a Merkle proof against roots set by the KarakMultisig, which can recover all remaining funds after 2027-09-12. No claim interface or Merkle treeA hash-based data structure in which each leaf node is a hash of a block of data, and each non-leaf node is a hash of its children. The root of the tree is a cryptographic fingerprint of the entire data structure. Merkle trees (Merkle Patricia Tries) are used in Ethereum to efficiently store key-value pairs. has been published. The only public notice is a Discord announcement from November 2025 asking users to unstake and bridgeA message-passing protocol between two blockchains. At its most basic, a token bridge consists of a smart contract which can escrow funds on one side of the bridge, and instruct the release or minting of corresponding assets on the other side, but bridges could also support arbitrary messages. How these instructions are validated is a critical factor in assessing the trust assumptions of a bridge. out by 2025-12-31.

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About

K2 is a general-purpose L2, which rebranded to the OpenGDP Network to soon become an asset tokenization-focused L1.


  • Total Value SecuredTVS
    $5.72 M1.60%
  • Past day UOPSDaily UOPS
    0.000.00%
  • Gas token
    ETH
  • Type
    Other

  • Purpose
    Universal
  • Chain ID
    2410

  • Tokens breakdown

    Sequencer failureState validationData availabilityExit windowProposer failure

    Badges

    About

    K2 is a general-purpose L2, which rebranded to the OpenGDP Network to soon become an asset tokenization-focused L1.

    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.

    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.


    Total
    Canonically BridgedCanonically Bridged ValueCanonical
    Natively MintedNatively Minted TokensNative
    Externally BridgedExternally Bridged ValueExternal

    ETH & derivatives
    Stablecoins
    BTC & derivatives
    Other
    Past Day UOPS
    Past Day Ops count
    Max. UOPS
    Past day UOPS/TPS Ratio

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



    Total cost
    Avg cost per L2 UOP
    Avg cost per day

    This section shows how much data the project publishes to its data-availability (DA) layer over time. The project currently posts data to; previously it posted toCelestiaCelestia.



    Data posted
    Avg size per day
    Avg size per L2 UOP

    This section shows how "live" the project's operators are by displaying how frequently they submit transactions of the selected type. It also highlights anomalies - significant deviations from their typical schedule.


    Avg. tx data subs. interval
    Avg. state updates interval

    K2 shut down, exits replaced by Merkle claims

    2026 Sep 15th

    Batch posting stopped; bridgeA message-passing protocol between two blockchains. At its most basic, a token bridge consists of a smart contract which can escrow funds on one side of the bridge, and instruct the release or minting of corresponding assets on the other side, but bridges could also support arbitrary messages. How these instructions are validated is a critical factor in assessing the trust assumptions of a bridge. contracts only allow Merkle-proof claims of escrowed funds.

    Learn more

    Karak rebrands to OpenGDP

    2025 Nov 17th

    Karak rebrands to OpenGDP.

    Learn more
    Fraud proof systemThe infrastructure that allows projects to verify their state transitions. It is composed by onchain verifiers and offchain provers. The main two flavors are optimistic and ZK proof systems, but they can be combined in a hybrid model. In general though, if a system is able to accept state roots optimistically, even if it has a ZK component, it is considered an optimistic proof system. is currently under development. Users need to trust the blockAn ordered list of transactions and chain-related metadata that gets bundled together and published to the L1/DA layer. Nodes execute the transactions contained within blocks to change the rollup chain’s state. Protocol rules dictate what constitutes a valid block, and invalid blocks are skipped over. proposerIn the context of L2s, the actor that proposes a claimed state root on L1. The term is also used in the context of Ethereum to refer to the actor that proposes a new block. to submit correct L1Layer 1 (L1) is a blockchain that is self-reliant on its validator set for its security and consensus properties. Ethereum is an example of a layer 1. Blockchains started receiving the moniker of layer 1 once layer 2 became a meaningful area of development. state rootsA cryptographic hash succinctly representing a state using a Merkle tree..
    Fraud proof systemThe infrastructure that allows projects to verify their state transitions. It is composed by onchain verifiers and offchain provers. The main two flavors are optimistic and ZK proof systems, but they can be combined in a hybrid model. In general though, if a system is able to accept state roots optimistically, even if it has a ZK component, it is considered an optimistic proof system. is currently under development. Users need to trust the blockAn ordered list of transactions and chain-related metadata that gets bundled together and published to the L1/DA layer. Nodes execute the transactions contained within blocks to change the rollup chain’s state. Protocol rules dictate what constitutes a valid block, and invalid blocks are skipped over. proposerIn the context of L2s, the actor that proposes a claimed state root on L1. The term is also used in the context of Ethereum to refer to the actor that proposes a new block. to submit correct L1Layer 1 (L1) is a blockchain that is self-reliant on its validator set for its security and consensus properties. Ethereum is an example of a layer 1. Blockchains started receiving the moniker of layer 1 once layer 2 became a meaningful area of development. state rootsA cryptographic hash succinctly representing a state using a Merkle tree..
    Sequencer failureState validationData availabilityExit windowProposer failure
    Sequencer failure
    Self sequence

    In the event of a sequencerA party responsible for ordering and executing transactions on the rollup. The sequencer verifies transactions, compresses the data into a block, and submits the data related to it to enable state reconstruction to Ethereum L1 as a single transaction. The data can be either transaction data or state diffs. failure, users can force transactions to be included in the project’s chain by sending them to L1Layer 1 (L1) is a blockchain that is self-reliant on its validator set for its security and consensus properties. Ethereum is an example of a layer 1. Blockchains started receiving the moniker of layer 1 once layer 2 became a meaningful area of development.. There can be up to a 12h delay on this operation.

    State validation
    None

    Currently the system permits invalid state rootsA cryptographic hash succinctly representing a state using a Merkle tree.. More details in project overview.

    Data availability
    External

    Proof construction and state derivation fully rely on data that is posted on Celestia. SequencerA party responsible for ordering and executing transactions on the rollup. The sequencer verifies transactions, compresses the data into a block, and submits the data related to it to enable state reconstruction to Ethereum L1 as a single transaction. The data can be either transaction data or state diffs. tx roots are not checked against the Blobstream bridgeA message-passing protocol between two blockchains. At its most basic, a token bridge consists of a smart contract which can escrow funds on one side of the bridge, and instruct the release or minting of corresponding assets on the other side, but bridges could also support arbitrary messages. How these instructions are validated is a critical factor in assessing the trust assumptions of a bridge. data roots onchain, but L2Layer 2 (L2) is a category of technical solutions aimed to scale the base layer in a trust minimized way. This category includes solutions like rollups as well as state channels and plasma. Other solutions are able to scale further, but with the introduction of additional trust assumptions, which are therefore not trust minimized. Sometimes the term Layer 2 is used to refer to include these solutions too, like validiums and optimiums, but to distinguish between trust minimized and non trust minimized solutions they are often referred to as "light" L2s, opposed to "strong" L2s like rollups. nodes can verify data availabilityThe property of a rollup's data being reachable by any node retrieving the data that were rolled up and executed to reach the proposed state. Data availability (DA), specifically decoupling it from the rollup nodes themselves, is one of the preeminent factors which allows a rollup to scale securely. A rollup is faced with a decision of what to use as a DA layer to guarantee that any node can retrieve this data--permissionlessly under any circumstance. For this reason, using Ethereum for DA currently provides the strongest security guarantees. If data is stored somewhere other than a permissionless L1, then the project is not a rollup, but rather a validium or an optimium. by running a Celestia light clientSometimes labelled interchangeably as a “node”, they are tasked with processing transactions and managing the blockchains's state. They run the computations for each transaction according to the rollup's virtual machine and protocol rules. If comparing to Ethereum clients, these would be execution clients such as Geth, as opposed to consensus clients..

    Exit window
    None

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

    Proposer failure
    Cannot withdraw

    Only the whitelisted proposers can publish state rootsA cryptographic hash succinctly representing a state using a Merkle tree. on L1Layer 1 (L1) is a blockchain that is self-reliant on its validator set for its security and consensus properties. Ethereum is an example of a layer 1. Blockchains started receiving the moniker of layer 1 once layer 2 became a meaningful area of development., so in the event of failure the withdrawals are frozen.

    K2
    K2 is not even a
    Stage 0
    project.

    Learn more about 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 is posted to Celestia

    Transactions roots are posted onchain and the full data is posted on Celestia. Since the Blobstream bridgeA message-passing protocol between two blockchains. At its most basic, a token bridge consists of a smart contract which can escrow funds on one side of the bridge, and instruct the release or minting of corresponding assets on the other side, but bridges could also support arbitrary messages. How these instructions are validated is a critical factor in assessing the trust assumptions of a bridge. is not used, availability of the data is not verified against Celestia validatorsIn the context of L2s, a Validator is an actor that validates the correctness of state transitions. For optimistic rollups this corresponds to challengers, and for ZK rollups this corresponds to the onchain verifier, meaning that the SequencerA party responsible for ordering and executing transactions on the rollup. The sequencer verifies transactions, compresses the data into a block, and submits the data related to it to enable state reconstruction to Ethereum L1 as a single transaction. The data can be either transaction data or state diffs. 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 - address
    4. OptimismPortal.sol - source code, depositTransaction function
    Learn more about the DA layer here: Celestia logoCelestia
    No state validation

    OP Stack projects can use the OP fault proof systemThe infrastructure that allows projects to verify their state transitions. It is composed by onchain verifiers and offchain provers. The main two flavors are optimistic and ZK proof systems, but they can be combined in a hybrid model. In general though, if a system is able to accept state roots optimistically, even if it has a ZK component, it is considered an optimistic 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 ProposerIn the context of L2s, the actor that proposes a claimed state root on L1. The term is also used in the context of Ethereum to refer to the actor that proposes a new block. and Challengers to ensure state correctness. The smart contract system permits invalid state rootsA cryptographic hash succinctly representing a state using a Merkle tree..

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

    1. L2OutputOracle.sol - source code, deleteL2Outputs function

    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
    2
    Last upgrade
    15d 7h ago
    Avg upgrade interval
    1y 4mo
    2026 September 16, 14:49 UTC
    High severity
    26changes

    K2 core bridge contracts replaced with a Merkle-claim exit mechanism; batch posting stopped. OptimismPortal implementation 0x3fe449Ef47228F03f979F9D955196494243cdf7E (v1.10.0) → 0xB1762246367681e5b335968950e8A17b0c56021D (v2.3.0), upgraded and paused by the KarakMultisig on 2026-09-15 04:45 UTC (tx 0x59515cbe7245d0856751523549d7b4524beb5f31930b2bc7bc3016b8071e65fd ). depositTransaction() , receive() , proveWithdrawalTransaction() and finalizeWithdrawalTransaction() now revert. Escrowed ETH (1876 ETH) is claimable via claimETH(amount, proof) against merkleRootETH = 0x6822879a8b8b0acb7a826beaec075d292958ffcb64c980959c0d0aea5ea0f8f9 , set on 2026-09-16 04:03 UTC (tx 0x2080dbdfa4798b9003dfe3e8b5bf8ea1772143eaf44acac1217002904eef87ec , which also unpaused the portal); leaf = keccak256(bytes.concat(keccak256(abi.encode(claimer, amount)))) , claims are cumulative per address. The Guardian can pause/unpause claims and, while paused and after RECOVERY TIMESTAMP = 1820707200 (2027-09-12), call recoverETH(recipient) for the full balance. https://disco.l2beat.com/diff/eth:0x3fe449Ef47228F03f979F9D955196494243cdf7E/eth:0xB1762246367681e5b335968950e8A17b0c56021D L1StandardBridge implementation 0xC4De51792746960FC0ac78360b8e9c6E103F3B13 (v1.4.0) → 0xF44B55E152e872FF5CbD3d9F3bd732F67d5B366A (v2.3.0) in the same tx. All deposit entrypoints and finalizeBridgeETH() / finalizeBridgeERC20() now revert. Escrowed ERC20s are claimable via claimTokens(tokens[], amounts[], proof[]) against merkleRoot = 0x0747603ccf64fdae7c52f9e69c1bafbb8b171860812139d59972cd8d022e3840 (set 2026-09-16 04:03 UTC); leaf = keccak256(bytes.concat(keccak256(abi.encode(claimer, tokens, amounts)))) , cumulative per claimer and token. The Guardian (read from the portal) can call recoverTokens(recipient, tokens[]) under the same paused + RECOVERY TIMESTAMP conditions, and sweepETH() while claims are paused to forward the bridge's ETH balance to the OptimismPortal. https://disco.l2beat.com/diff/eth:0xC4De51792746960FC0ac78360b8e9c6E103F3B13/eth:0xF44B55E152e872FF5CbD3d9F3bd732F67d5B366A Batcher 0x84BdFb21ed7C8B332a42bFD595744a84F3101e4E last posted to the inbox on 2026-09-15 01:22:59 UTC; L2 blocks since then are empty sequencer-window blocks. Proposer 0x4179f43f3b994e97090557363b09F403138a729e keeps posting output roots for them every 7200 blocks (last 2026-09-16 13:49 UTC, L2 block 43063200). Last withdrawal initiated on L2 2026-09-13 18:51 UTC; withdrawals not finalized before the upgrade cannot be finalized. No claims executed yet; no public Merkle tree or announcement of the claim mechanism found.

    contract KarakMultisig (eth:0x28A227d4faF0f4f75897438E24C43EF1CDABb920) [GnosisSafe] {
    +++ description: None
    receivedPermissions.3:
    + {"permission":"interact","from":"eth:0xBA61F25dd9f2d5f02D01B1C2c1c5F0B14c4B48A3","description":"set merkleRoot, sweep the bridge's ETH into the OptimismPortal while claims are paused, and after the recovery timestamp withdraw all tokens and ETH.","role":".guardian"}
    receivedPermissions.3.description:
    - "Allowed to pause withdrawals. In op stack systems with a proof system, the Guardian can also blacklist dispute games and set the respected game type (permissioned / permissionless)."
    + "set merkleRootETH, pause and unpause claims, and after RECOVERY_TIMESTAMP (while paused) withdraw the whole ETH balance."
    receivedPermissions.4.description:
    - "Allowed to pause withdrawals. In op stack systems with a proof system, the Guardian can also blacklist dispute games and set the respected game type (permissioned / permissionless)."
    + "set merkleRootETH, pause and unpause claims, and after RECOVERY_TIMESTAMP (while paused) withdraw the whole ETH balance."
    }
    contract L1StandardBridge (eth:0xBA61F25dd9f2d5f02D01B1C2c1c5F0B14c4B48A3) [opstack/L1StandardBridge_K2_claim] {
    +++ description: Modified L1StandardBridge: deposits and finalizing withdrawals are disabled. ERC20 tokens held by the contract can only be claimed with a Merkle proof against merkleRoot. After the recovery timestamp and while claims are paused (both read from OPTIMISM_PORTAL), the guardian can withdraw all tokens and ETH.
    template:
    - "opstack/L1StandardBridge"
    + "opstack/L1StandardBridge_K2_claim"
    sourceHashes.1:
    - "0x59c3a5c6d2b22ffe8a2e4bc09e8deb308fa757230ac6f0f854c7bd1244755f8d"
    + "0x32ea980305b615ec390e8c57663c0734c2ebf70465e6076b26eb8262e7400dba"
    description:
    - "The main entry point to deposit ERC20 tokens from host chain to this chain."
    + "Modified L1StandardBridge: deposits and finalizing withdrawals are disabled. ERC20 tokens held by the contract can only be claimed with a Merkle proof against merkleRoot. After the recovery timestamp and while claims are paused (both read from OPTIMISM_PORTAL), the guardian can withdraw all tokens and ETH."
    values.$implementation:
    - "eth:0xC4De51792746960FC0ac78360b8e9c6E103F3B13"
    + "eth:0xF44B55E152e872FF5CbD3d9F3bd732F67d5B366A"
    values.version:
    - "1.4.0"
    + "2.3.0"
    values.guardian:
    + "eth:0x28A227d4faF0f4f75897438E24C43EF1CDABb920"
    +++ description: Root of the Merkle tree of (address, tokens, cumulative amounts) ERC20 claims.
    values.merkleRoot:
    + "0x0747603ccf64fdae7c52f9e69c1bafbb8b171860812139d59972cd8d022e3840"
    values.OPTIMISM_PORTAL:
    + "eth:0xeeCE9CD7Abd1CC84d9dfc7493e7e68079E47eA73"
    implementationNames.eth:0xC4De51792746960FC0ac78360b8e9c6E103F3B13:
    - "L1StandardBridge"
    implementationNames.eth:0xF44B55E152e872FF5CbD3d9F3bd732F67d5B366A:
    + "L1StandardBridge"
    fieldMeta:
    + {"merkleRoot":{"description":"Root of the Merkle tree of (address, tokens, cumulative amounts) ERC20 claims."}}
    }
    contract OptimismPortal (eth:0xeeCE9CD7Abd1CC84d9dfc7493e7e68079E47eA73) [opstack/OptimismPortal_K2_claim] {
    +++ description: Modified OptimismPortal: deposits, proving and finalizing withdrawals are disabled. ETH held by the contract can only be claimed with a Merkle proof against merkleRootETH. After RECOVERY_TIMESTAMP and while claims are paused, the guardian can withdraw the whole ETH balance.
    template:
    - "opstack/OptimismPortal"
    + "opstack/OptimismPortal_K2_claim"
    sourceHashes.1:
    - "0x620d0104aa94a7390fc59343e3d3a822959da7dc77b3a42f65586020da2e4faf"
    + "0x094c023344df46deb39df74619a815bc1bfced43ad55bb1f9dbb4e9c8718ba65"
    description:
    - "The main entry point to deposit funds from host chain to this chain. It also allows to prove and finalize withdrawals."
    + "Modified OptimismPortal: deposits, proving and finalizing withdrawals are disabled. ETH held by the contract can only be claimed with a Merkle proof against merkleRootETH. After RECOVERY_TIMESTAMP and while claims are paused, the guardian can withdraw the whole ETH balance."
    values.$implementation:
    - "eth:0x3fe449Ef47228F03f979F9D955196494243cdf7E"
    + "eth:0xB1762246367681e5b335968950e8A17b0c56021D"
    values.$pastUpgrades.1:
    + ["2026-09-15T04:45:35.000Z","0x59515cbe7245d0856751523549d7b4524beb5f31930b2bc7bc3016b8071e65fd",["eth:0xB1762246367681e5b335968950e8A17b0c56021D"]]
    values.$upgradeCount:
    - 1
    + 2
    values.version:
    - "1.10.0"
    + "2.3.0"
    +++ description: Root of the Merkle tree of (address, cumulative amount) ETH claims.
    values.merkleRootETH:
    + "0x6822879a8b8b0acb7a826beaec075d292958ffcb64c980959c0d0aea5ea0f8f9"
    +++ description: Timestamp after which the guardian can withdraw the whole ETH balance.
    values.RECOVERY_TIMESTAMP:
    + 1820707200
    implementationNames.eth:0x3fe449Ef47228F03f979F9D955196494243cdf7E:
    - "OptimismPortal"
    implementationNames.eth:0xB1762246367681e5b335968950e8A17b0c56021D:
    + "OptimismPortal"
    fieldMeta:
    + {"merkleRootETH":{"description":"Root of the Merkle tree of (address, cumulative amount) ETH claims."},"RECOVERY_TIMESTAMP":{"description":"Timestamp after which the guardian can withdraw the whole ETH balance."}}
    }
    2026 July 09, 09:57 UTC
    1change

    SystemConfig opStackDA.isUsingCelestia: false → true . K2 is posting to Celestia again after the brief switch to Ethereum calldata on 2026-07-01; that switch was transient and has been removed from the config.

    contract SystemConfig (eth:0x622333688CC1878C7ff4205c89bDe051798788A7) [opstack/SystemConfig] {
    +++ description: Contains configuration parameters such as the Sequencer address, gas limit on this chain and the unsafe block signer address.
    values.opStackDA.isUsingCelestia:
    - false
    + true
    }
    2026 July 01, 16:32 UTC
    1change

    SystemConfig opStackDA.isUsingCelestia : true → false . Karak no longer uses Celestia DA.

    contract SystemConfig (eth:0x622333688CC1878C7ff4205c89bDe051798788A7) [opstack/SystemConfig] {
    +++ description: Contains configuration parameters such as the Sequencer address, gas limit on this chain and the unsafe block signer address.
    values.opStackDA.isUsingCelestia:
    - true
    + false
    }
    2025 December 12, 10:25 UTC
    1change

    K2 is posting to Celestia.

    contract SystemConfig (eth:0x622333688CC1878C7ff4205c89bDe051798788A7) {
    +++ description: Contains configuration parameters such as the Sequencer address, gas limit on this chain and the unsafe block signer address.
    values.opStackDA.isUsingCelestia:
    - false
    + true
    }
    2025 November 28, 12:50 UTC
    1change

    Posts calldata instead of Celestia blobs.

    contract SystemConfig (eth:0x622333688CC1878C7ff4205c89bDe051798788A7) {
    +++ description: Contains configuration parameters such as the Sequencer address, gas limit on this chain and the unsafe block signer address.
    values.opStackDA.isUsingCelestia:
    - true
    + false
    }

    The system has a centralized operator

    The operatorAn operator is the entity charged with managing a rollup and progressing its state. A rollup operator can be a centralized sequencer, proposer, prover, challenger, pauser of admin that is able to perform upgrades. is the only entity that can propose blocksAn ordered list of transactions and chain-related metadata that gets bundled together and published to the L1/DA layer. Nodes execute the transactions contained within blocks to change the rollup chain’s state. Protocol rules dictate what constitutes a valid block, and invalid blocks are skipped over.. 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 - source code, CHALLENGER address
    2. L2OutputOracle.sol - 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 - source code, depositTransaction function

    Regular messaging

    The user initiates L2Layer 2 (L2) is a category of technical solutions aimed to scale the base layer in a trust minimized way. This category includes solutions like rollups as well as state channels and plasma. Other solutions are able to scale further, but with the introduction of additional trust assumptions, which are therefore not trust minimized. Sometimes the term Layer 2 is used to refer to include these solutions too, like validiums and optimiums, but to distinguish between trust minimized and non trust minimized solutions they are often referred to as "light" L2s, opposed to "strong" L2s like rollups.->L1Layer 1 (L1) is a blockchain that is self-reliant on its validator set for its security and consensus properties. Ethereum is an example of a layer 1. Blockchains started receiving the moniker of layer 1 once layer 2 became a meaningful area of development. messages by submitting a regular transaction on this chain. When the blockAn ordered list of transactions and chain-related metadata that gets bundled together and published to the L1/DA layer. Nodes execute the transactions contained within blocks to change the rollup chain’s state. Protocol rules dictate what constitutes a valid block, and invalid blocks are skipped over. containing that transaction is settled, the message becomes available for processing on L1. The process of block finalization takes a challenge periodIn optimistic rollups, the window of time wherein network participants can assert that some fraud was included in a prior block. Most optimistic rollups currently specify a challenge window of 7 days. By extending the period, there is more time for participants to guard against fraud (invalid state transitions), but also more time until withdrawals gets enabled. of 3d to complete.

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

    Forced messaging

    If the user experiences censorship from the operatorAn operator is the entity charged with managing a rollup and progressing its state. A rollup operator can be a centralized sequencer, proposer, prover, challenger, pauser of admin that is able to perform upgrades. with regular L2Layer 2 (L2) is a category of technical solutions aimed to scale the base layer in a trust minimized way. This category includes solutions like rollups as well as state channels and plasma. Other solutions are able to scale further, but with the introduction of additional trust assumptions, which are therefore not trust minimized. Sometimes the term Layer 2 is used to refer to include these solutions too, like validiums and optimiums, but to distinguish between trust minimized and non trust minimized solutions they are often referred to as "light" L2s, opposed to "strong" L2s like rollups.->L1Layer 1 (L1) is a blockchain that is self-reliant on its validator set for its security and consensus properties. Ethereum is an example of a layer 1. Blockchains started receiving the moniker of layer 1 once layer 2 became a meaningful area of development. messaging they can submit their messages directly on L1. The system is then obliged to service this request or halt all messages, including forced withdrawals from L1 and regular messages initiated on L2. Once the force operation is submitted and if the request is serviced, the operation follows the flow of a regular message.

    1. Forced withdrawal from an OP Stack blockchain

    EVM compatible smart contracts are supported

    OP stack chains are pursuing the EVM EquivalenceA perfect degree of compatibility; where one system or concept is indistinguishable from another in the domain being compared. In the context of rollups, it generally refers to the proximity to the EVM and to Ethereum architecture. model. No changes to smart contracts are required regardless of the language they are written in, i.e. anything deployed on L1Layer 1 (L1) is a blockchain that is self-reliant on its validator set for its security and consensus properties. Ethereum is an example of a layer 1. Blockchains started receiving the moniker of layer 1 once layer 2 became a meaningful area of development. can be deployed on L2Layer 2 (L2) is a category of technical solutions aimed to scale the base layer in a trust minimized way. This category includes solutions like rollups as well as state channels and plasma. Other solutions are able to scale further, but with the introduction of additional trust assumptions, which are therefore not trust minimized. Sometimes the term Layer 2 is used to refer to include these solutions too, like validiums and optimiums, but to distinguish between trust minimized and non trust minimized solutions they are often referred to as "light" L2s, opposed to "strong" L2s like rollups..

    1. Introducing EVM Equivalence
    A dashboard to explore contracts and permissions
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    Ethereum

    Actors:

    KarakMultisig0x28A2…b920

    A Multisig with 3/5 threshold.

    • Can upgrade with no delay
      • L2OutputOracle
      • SystemConfig
      • L1ERC721Bridge
      • L1CrossDomainMessenger
      • L1StandardBridge
      • OptimismPortal
      • OptimismMintableERC20Factory
    • Can interact with L2OutputOracle
      • Allowed to challenge or delete state rootsA cryptographic hash succinctly representing a state using a Merkle tree. proposed by a ProposerIn the context of L2s, the actor that proposes a claimed state root on L1. The term is also used in the context of Ethereum to refer to the actor that proposes a new block.
    • Can interact with SystemConfig
      • it can update the preconfer address, the batch submitter (SequencerA party responsible for ordering and executing transactions on the rollup. The sequencer verifies transactions, compresses the data into a block, and submits the data related to it to enable state reconstruction to Ethereum L1 as a single transaction. The data can be either transaction data or state diffs.) address and the gasA virtual fuel used to execute smart contracts on a rollup. The EVM (or other VM within the rollup) uses an accounting mechanism to correspond the consumption of gas to the consumption of computing resources, and to limit the consumption of computing resources. configuration of the system
    • Can interact with L1StandardBridge
      • set merkleRoot, sweep the bridgeA message-passing protocol between two blockchains. At its most basic, a token bridge consists of a smart contract which can escrow funds on one side of the bridge, and instruct the release or minting of corresponding assets on the other side, but bridges could also support arbitrary messages. How these instructions are validated is a critical factor in assessing the trust assumptions of a bridge.’s ETH into the OptimismPortal while claims are paused, and after the recovery timestamp withdraw all tokens and ETH
    • Can interact with OptimismPortal
      • set merkleRootETH, pause and unpause claims, and after RECOVERY_TIMESTAMP (while paused) withdraw the whole ETH balance
    • Can interact with AddressManager
      • set and change address mappings
    • Can interact with L2OutputOracle
      • Allowed to post new state rootsA cryptographic hash succinctly representing a state using a Merkle tree. of the current layer to the host chain
    • Can interact with SystemConfig
      • Allowed to commit transactions from the current layer to the host chain
    A dashboard to explore contracts and permissions
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    A diagram of the smart contract architecture
    A diagram of the smart contract architecture

    Ethereum

    Contains a list of proposed state rootsA cryptographic hash succinctly representing a state using a Merkle tree. which Proposers assert to be a result of blockAn ordered list of transactions and chain-related metadata that gets bundled together and published to the L1/DA layer. Nodes execute the transactions contained within blocks to change the rollup chain’s state. Protocol rules dictate what constitutes a valid block, and invalid blocks are skipped over. execution. Currently only the PROPOSERIn the context of L2s, the actor that proposes a claimed state root on L1. The term is also used in the context of Ethereum to refer to the actor that proposes a new block. address can submit new state roots.

    • Roles:
      • admin: ProxyAdmin; ultimately KarakMultisig
      • challenger: KarakMultisig
      • proposer: EOA 1
    Can be upgraded by:

    Contains configuration parameters such as the SequencerA party responsible for ordering and executing transactions on the rollup. The sequencer verifies transactions, compresses the data into a block, and submits the data related to it to enable state reconstruction to Ethereum L1 as a single transaction. The data can be either transaction data or state diffs. address, gas limitThe maximum amount of gas a transaction or block may consume. on this chain and the unsafe blockAn ordered list of transactions and chain-related metadata that gets bundled together and published to the L1/DA layer. Nodes execute the transactions contained within blocks to change the rollup chain’s state. Protocol rules dictate what constitutes a valid block, and invalid blocks are skipped over. signer address.

    • Roles:
      • admin: ProxyAdmin; ultimately KarakMultisig
      • batcherHash: EOA 2
      • owner: KarakMultisig
    Can be upgraded by:

    Modified OptimismPortal: deposits, proving and finalizing withdrawals are disabled. ETH held by the contract can only be claimed with a Merkle proof against merkleRootETH. After RECOVERY_TIMESTAMP and while claims are paused, the guardian can withdraw the whole ETH balance.

    • Roles:
      • admin: ProxyAdmin; ultimately KarakMultisig
      • guardian: KarakMultisig
    The following tokens are included in the value secured calculation:
    ETH token logo
    Can be upgraded by:

    Used to bridgeA message-passing protocol between two blockchains. At its most basic, a token bridge consists of a smart contract which can escrow funds on one side of the bridge, and instruct the release or minting of corresponding assets on the other side, but bridges could also support arbitrary messages. How these instructions are validated is a critical factor in assessing the trust assumptions of a bridge. ERC-721 tokens from host chain to this chain.

    • Roles:
      • admin: ProxyAdmin; ultimately KarakMultisig
    Can be upgraded by:

    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 limitThe maximum amount of gas a transaction or block may consume., it can be resubmitted via this contract’s replay function.

    • Roles:
      • admin: ProxyAdmin; ultimately KarakMultisig
    Can be upgraded by:

    Modified L1StandardBridge: deposits and finalizing withdrawals are disabled. ERC20 tokens held by the contract can only be claimed with a Merkle proof against merkleRoot. After the recovery timestamp and while claims are paused (both read from OPTIMISM_PORTAL), the guardian can withdraw all tokens and ETH.

    • Roles:
      • admin: ProxyAdmin; ultimately KarakMultisig
      • guardian: KarakMultisig

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

    Can be upgraded by:
    ProxyAdmin0x1612…065C
    • Roles:
      • owner: KarakMultisig

    A helper contract that generates OptimismMintableERC20 contracts on the networkA constellation of nodes (peers) that communicate via a peer-to-peer protocol, for example, in propagating transactions and blocks to other nodes. it’s deployed to. OptimismMintableERC20 is a standard extension of the base ERC20 token contract designed to allow the L1StandardBridge contracts to mint and burn tokens. This makes it possible to use an OptimismMintableERC20 as this chain’s representation of a token on the host chain, or vice-versa.

    • Roles:
      • admin: ProxyAdmin; ultimately KarakMultisig
    Can be upgraded by:

    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).