Butter Network

OpenZeppelin AccessManager-derived authority for Butter’s restricted 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. and FeeService functions. Its role configuration controls who can change bridge validation dependencies, relay and token settings, fee parameters, pause state, and implementation upgrades.

• Roles:
  • adminRole: SafeL2

Butter’s Base 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. endpoint. Outbound transfers lock or burn assets and emit messages for the MAP relay chain; inbound transfers execute only after a LightNode-validated receipt proof for the configured MAP relay contract. The bridge can mint configured mintable tokens, release escrowed assets, and invoke receiver callbacks, so compromise of validation, relay configuration, or management authority can lead to loss of bridged funds.

• Roles:
  • authority: Butter AuthorityManager

Upgradeable MAP relay-chain 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. used by Butter bridges. It verifies relay-chain headers with the stored BLS validatorIn 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 set and verifies receipt Merkle proofsHashing the pairs of values at each level and climbing up the (Merkle) Tree until you obtain the root hash. Merkle proofs help check if the data belongs to a set without having to store the entire set. against accepted headers. It is the destination-chain validation boundary for bridged messages.

• Roles:
  • admin: EOA 1

Cryptographic and RLP/Merkle-proof helper contract called by the Butter MAP LightNode to validate relay-chain headers and transaction receipts.

Fee configuration contract used by Butter 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. to calculate cross-chain message fees and select the fee recipient.

• Roles:
  • authority: Butter AuthorityManager