Crate bal_codec 

bal-codec

EIP-7928 Block-Level Access List: RLP decoding, ordering/uniqueness validation, keccak256(rlp(bal)), and verification against the header’s blockAccessListHash. Knows nothing about Solidity, storage, or nodes — this is the one crate a spec change touches.

use bal_codec::{BlockAccessList, EMPTY_BAL_HASH};

// The empty BAL is `rlp([])` = 0xc0; its hash is fixed by the EIP.
let bal = BlockAccessList::decode(&[0xc0])?;
assert!(bal.is_empty());
assert_eq!(bal.hash(), EMPTY_BAL_HASH);
bal.verify(EMPTY_BAL_HASH)?;

With the json feature, the execution-apis JSON form served by eth_getBlockAccessList decodes through the same validation:

let v: serde_json::Value = rpc_response["result"].clone();
let bal = BlockAccessList::from_rpc_json(&v)?;
assert_eq!(bal.hash(), header.block_access_list_hash);

Lookups use the sorted order the EIP mandates: bal.account(&addr) and account.slot(&key) are binary searches. A BAL that violates ordering or uniqueness is rejected, never softly accepted.

Part of balq.

EIP-7928 Block-Level Access List codec.

This crate is the only place the 7928 wire format is known. Everything above it (archive, layout, cli) consumes the typed structures and must not touch RLP.

Wire schema (from the EIP, Review status, subject to change):

StorageChange   = [BlockAccessIndex(u32), StorageValue(u256)]
BalanceChange   = [BlockAccessIndex(u32), Balance(u256)]
NonceChange     = [BlockAccessIndex(u32), Nonce(u64)]
CodeChange      = [BlockAccessIndex(u32), Bytecode(bytes)]
SlotChanges     = [StorageKey(u256), [StorageChange...]]
AccountChanges  = [Address, [SlotChanges...], [StorageKey...],
                   [BalanceChange...], [NonceChange...], [CodeChange...]]
BlockAccessList = [AccountChanges...]
block_access_list_hash = keccak256(rlp(BlockAccessList))

Ordering is part of validity: accounts by address, slots by key, changes by index, all strictly ascending. A BAL that violates ordering or uniqueness is rejected by BlockAccessList::decode; it is never softly accepted.

With the json feature, BlockAccessList::from_rpc_json accepts the execution-apis JSON form served by eth_getBlockAccessList.

Structs

AccountChanges

Everything that happened to one account within the block.

BalanceChange

One balance change.

BlockAccessList

The whole list. Wire form is a bare RLP list of AccountChanges (no wrapping struct), so encoding is transparent over accounts.

CodeChange

One code change (deployment or self-destruct).

NonceChange

One nonce change.

SlotChanges

All writes to one slot within the block.

StorageChange

One write to a storage slot.

Enums

CodecError

Decoding, validation and verification failures.

Constants

EMPTY_BAL_HASH

Hash of the empty BAL: keccak256(rlp([])) = keccak256(0xc0).

Type Aliases

BlockAccessIndex

Position of a change in the block’s life cycle. 0 = pre-execution system calls, 1..=n = transactions, n+1 = post-execution.