Kroma

The L2OutputOracle contract contains a list of proposed state roots which Proposers assert to be a result of block execution. Anyone can participate as a Proposer by depositing in the ValidatorPool. A root can be proposed every 1800 blocks (2s block time).

• A timelock with access control. The current minimum delay is 0s.
• Can act on behalf of ProxyAdmin.
• Can be used to interact with TimeLock - manage all access control roles.
• Can be used to interact with SystemConfig - it can update the preconfer address, the batch submitter (Sequencer) address and the gas configuration of the system.
• Can be used to upgrade implementation of USDCBridge.

Manages the set of Proposers (Validators in Kroma) and selects the next proposer with the window to submit the output root within 30m, after which anyone can propose for them. It is also the entry point for other contracts, such as the L2OutputOracle and the Colosseum, which distribute output rewards and slash challenge losers. It makes successive calls to the AssetManager to apply changes to the proposers’ assets.

This is a fork of the standard OP stack OptimismPortal contract, the main entry point to deposit funds from L1 to L2. It also allows to prove and finalize withdrawals. This contract stores the following tokens: ETH.

Merkle Trie contract used to prove withdrawals that were initiated in the legacy system, deprecated for new withdrawals and succeeded by a merkle tree library in the KromaPortal.

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

This contract is the router for zk proof verification. It stores the mapping between identifiers and the address of onchain verifier contracts, routing each identifier to the corresponding verifier contract.

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.

Used to bridge ERC-721 tokens from host chain to this chain.

• Can be used to upgrade implementation of ZKProofVerifier, L2OutputOracle, TimeLock, ValidatorManager, KromaPortal, SystemConfig, KromaSecurityCouncil, L1CrossDomainMessenger, L1ERC721Bridge, ZkVerifier, Colosseum, AssetManager, UpgradeGovernor, SecurityCouncilTokenOwners, ValidatorPool.
• Can be used to upgrade implementation of L1StandardBridge - upgrading the bridge implementation can give access to all funds escrowed therein.

ZK verifier used to verify the last step of a legacy zkEVM proof, which corresponds to a block.

Contract used to challenge state roots and prove fraud. If successful, the wrong state root in the L2OutputOracle is replaced.

This contract stores the following tokens: USDC.

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

Manages the delegation and undelegation of KRO tokens and Kroma Guardian House (KGH) NFTs for Proposers (Kroma Validators) and distributes rewards.

• A governance proxy contract using token voting with SecurityCouncilTokenOwners as identification of actors allowed to vote/sign a proposal which is passed to the TimeLock afterwards.
• Can act on behalf of TimeLock.
• Can be used to interact with TimeLock - cancel queued transactions.
• Can be used to interact with TimeLock - execute transactions that are ready.
• Can be used to interact with TimeLock - manage all access control roles.
• Can be used to interact with TimeLock - propose transactions.

Contract used to compute hashes. It is used by the ZKMerkeTrie. The contract has been generated using the circomlibjs library.

Contract used to manage the Proposers. Anyone can submit a deposit and bond to a state root, or create a challenge. It also manages the Proposer rotation for each submittable block using a random selection. If the selected proposer fails to publish a root within 30m then the submission becomes open to everyone.