Struct ExecutionChainFetcher

pub struct ExecutionChainFetcher {
    api_client: ApiClient,
    rpc_url: String,
    network_id: u64,
}

Fetcher for EVM execution layer data with MMR proofs

This fetcher retrieves execution layer (EL) blockchain data such as headers, accounts, and transactions, along with the MMR proofs needed to decommit headers from STWO proofs.

The typical flow is:

1. Fetch a header with its MMR proof
2. Use the MMR proof to decommit and verify the header from the STWO block proof
3. Use the verified header to verify accounts/transactions via standard Merkle proofs

Fields

api_client: ApiClient

rpc_url: String

network_id: u64

Implementations

impl ExecutionChainFetcher

pub fn new(api_client: ApiClient, rpc_url: String, network_id: u64) -> Self

Creates a new execution chain fetcher

Arguments

• api_client - The Bankai API client for fetching MMR proofs
• rpc_url - The EVM RPC endpoint URL
• network_id - The network ID for this chain

pub async fn header( &self, block_number: u64, hashing_function: HashingFunctionDto, bankai_block_number: u64, ) -> SdkResult<ExecutionHeaderProof>

Fetches an execution header with its MMR proof

This retrieves the execution layer header from the RPC and generates an MMR proof that can be used to decommit this header from the STWO block proof’s execution MMR.

Arguments

• block_number - The block number to fetch
• hashing_function - The hash function to use for the MMR proof
• bankai_block_number - The Bankai block number containing the MMR

Returns

An ExecutionHeaderProof containing the header and MMR proof for decommitment

pub async fn header_only(&self, block_number: u64) -> SdkResult<ExecutionHeader>

Fetches an execution header without an MMR proof

Used internally by the batch builder. For verification purposes, use header() instead to get the header with its MMR proof.

pub fn network_id(&self) -> u64

Returns the network ID for this fetcher

pub async fn account( &self, block_number: u64, address: Address, _hashing_function: HashingFunctionDto, _bankai_block_number: u64, ) -> SdkResult<EIP1186AccountProofResponse>

Fetches an account proof for a specific address at a given block

Returns a Merkle proof that can verify the account’s state (balance, nonce, code hash, storage root) against the state root in the block header. The header itself must be verified first using an MMR proof.

Arguments

• block_number - The block number to query
• address - The account address
• _hashing_function - Reserved for future use
• _bankai_block_number - Reserved for future use

Returns

An EIP-1186 account proof that can be verified against the header’s state root

pub async fn tx_proof(&self, tx_hash: FixedBytes<32>) -> SdkResult<TxProof>

Fetches a transaction proof for a specific transaction hash

Returns the transaction data along with a Merkle proof that can verify the transaction against the transactions root in the block header. The header itself must be verified first using an MMR proof.

Arguments

• tx_hash - The transaction hash

Returns

A transaction proof containing the transaction and its Merkle proof

pub async fn storage_slot_proof( &self, block_number: u64, address: Address, slot_keys: &[U256], _hashing_function: HashingFunctionDto, _bankai_block_number: u64, ) -> SdkResult<StorageSlotProof>

Fetches storage slot proofs for one or more slots from a contract at a given block.

This calls the EIP-1186 eth_getProof RPC with the provided storage keys and returns the slot values along with the MPT proofs needed to verify them against the contract’s storage root (which itself can be verified against the header’s state root).

Arguments

• block_number - The block number to query
• address - The contract address
• slot_keys - The storage keys (uint256) to query
• _hashing_function - Reserved for future use
• _bankai_block_number - Reserved for future use