Block-level Access Lists (BALs)
Many thanks to Francesco, Jochem, Vitalik, Ignacio, Gary, Dankrad, Carl, Ansgar, and Tim for feedback and review.
bal_preview
TL;DR: Block builders include access lists...

<div><h1><a href="https://ethresear.ch#p-54283-block-level-access-lists-bals-1" rel="nofollow"></a>Block-level Access Lists (BALs)</h1><blockquote>Many thanks to <a href="https://x.com/fradamt" rel="nofollow">Francesco</a>, <a href="https://x.com/JochemBrouwer96" rel="nofollow">Jochem</a>, <a href="https://x.com/VitalikButerin" rel="nofollow">Vitalik</a>, <a href="https://x.com/ignaciohagopian" rel="nofollow">Ignacio</a>, <a href="https://x.com/gary_rong" rel="nofollow">Gary</a>, <a href="https://x.com/dankrad" rel="nofollow">Dankrad</a>, <a href="https://x.com/CarlBeek" rel="nofollow">Carl</a>, <a href="https://x.com/adietrichs" rel="nofollow">Ansgar</a>, and <a href="https://x.com/TimBeiko" rel="nofollow">Tim</a> for feedback and review.</blockquote><div><a href="https://ethresear.ch/uploads/default/original/3X/a/4/a4bd446262b8310169e42643ac48941f96ff572a.jpeg" title="bal_preview" rel="nofollow"><img src="https://ethresear.ch/uploads/default/optimized/3X/a/4/a4bd446262b8310169e42643ac48941f96ff572a_2_432x375.jpeg" alt="bal_preview"><div>bal_preview1024×888 145 KB</div></a></div>TL;DR: Block builders include access lists and state diffs into blocks for validators to validate faster → scale L1!One of the key topics in the renewed effort to scale Ethereum’s Layer 1—especially the execution layer—is <a href="https://github.com/ethereum/EIPs/blob/master/EIPS/eip-7928.md" rel="nofollow">block-level access lists (BALs) - EIP-7928</a>.BALs are structured lists that the block builder must include in each block, specifying which storage slots individual transactions will access. If these lists are inaccurate or incomplete, the block becomes invalid. As a result, Ethereum’s consensus mechanism can enforce strict compliance, requiring builders to provide correct BALs.Validators benefit significantly from BALs by accelerating block verification. Knowing exactly which accounts and storage slots will be accessed enables validators to apply simple parallelization strategies for disk reads (IO) and execution (EVM). This can lead to faster block validation and open the door to raising gas limits in the future.<blockquote>See Dankrad’s simulations on parallelizing storage reads <a href="https://notes.ethereum.org/@dankrad/SJawZpx1yx" rel="nofollow">here</a>.</blockquote>A critical design goal for BALs is maintaining compact size in both average and worst-case scenarios. Bandwidth is already a constraint for nodes and validators, so it’s vital that BALs don’t add unnecessary load to the network. BALs will be put into the block body, with a hash of the BAL stored in the header.<blockquote>Currently, Ethereum clients rely on their own optimistic parallelization strategies. These generally perform well on average blocks, but struggle with worst-case scenarios, leading to significant performance differences.</blockquote><h1><a href="https://ethresear.ch#p-54283-the-design-space-for-bals-2" rel="nofollow"></a>The design space for BALs</h1><ul><li>What to include?<ul><li>In addition to storage locations <code>(address, storage key)</code>, we can also include:<ul><li>storage values</li><li>balances</li><li>balance diffs</li></ul></li><li>For storage values, we can distinguish between:<ul><li>pre-block vs. pre-transaction execution values</li><li>pre- vs. post-transaction execution values</li></ul></li><li>Are we aiming to be hardware-agnostic, or do we want to optimize for certain commonly used hardware specs?</li></ul></li></ul>In the following, we’ll focus on three main variants of BALs: access, execution and state.<h1><a href="https://ethresear.ch#p-54283-access-bals-3" rel="nofollow"></a>Access BALs</h1>Access BALs map transactions to <code>(address, storage key)</code> tuples.<ul><li>Small in size.</li><li>Enable parallel disk reads but are less effective for parallel transaction validation due to potential dependencies.</li><li>Execution time is <code>parallel IO + serial EVM</code>.</li></ul>For efficiency, a lightweight BAL structure could look like this using SSZ:<pre><div><button></button><button></button></div><code># Type aliasesAddress = ByteVector(20)StorageKey = ByteVector(32)TxIndex = uint16# Constants; chosen to support a 630m block gas limitMAX_TXS = 30_000MAX_SLOTS = 300_000MAX_ACCOUNTS = 300_000# Containersclass SlotAccess(Container):slot: StorageKeytx_indices: List[TxIndex, MAX_TXS] # Transactions (by index) that access this slot (read or write)class AccountAccess(Container):address: Addressaccesses: List[SlotAccess, MAX_SLOTS]# Top-level block fieldsBlockAccessWrites = List[AccountAccess, MAX_ACCOUNTS]BlockAccessReads = List[AccountAccess, MAX_ACCOUNTS]</code></pre>The outer list is a deduplicated list of addresses accessed during the block.<ul><li>For each address, there’s a list of storage keys accessed.</li><li>For each storage key:<ul><li><code>List[TxIndex]</code>: Ordered transaction indices that accessed this key.</li></ul></li></ul>For example, the BAL for block number <code>21_935_797</code> would look like this:<pre><div><button></button><button></button></div><code>[('0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',[('0xa63b...c2', [0]),('0x8b3e...a7', [0]),('0xfb19...a8',[1, 2, 3, 4, 84, 85, 91]),# ... additional entries]),# ... additional entries]</code></pre><h1><a href="https://ethresear.ch#p-54283-execution-bals-4" rel="nofollow"></a>Execution BALs</h1>Execution BALs map transactions to <code>(address, storage key, value)</code> tuples and include balance diffs.<ul><li>Slightly larger in size due to value inclusion.</li><li>Facilitate parallel disk reads and parallel execution.</li><li>Execution time is <code>parallel IO + parallel EVM</code>.</li></ul>An efficient structure using SSZ:<pre><div><button></button><button></button></div><code># Type aliasesAddress = ByteVector(20)StorageKey = ByteVector(32)StorageValue = ByteVector(32)TxIndex = uint16Nonce = uint64# Constants; chosen to support a 630m block gas limitMAX_TXS = 30_000MAX_SLOTS = 300_000MAX_ACCOUNTS = 300_000MAX_CODE_SIZE = 24576 # Maximum contract bytecode size in bytes# SSZ containersclass PerTxAccess(Container):tx_index: TxIndexvalue_after: StorageValue # value in state after the last access within the transactionclass SlotAccess(Container):slot: StorageKeyaccesses: List[PerTxAccess, MAX_TXS] # empty for readsclass AccountAccess(Container):address: Addressaccesses: List[SlotAccess, MAX_SLOTS]code: Union[ByteVector(MAX_CODE_SIZE), None] # Optional field for contract bytecodeBlockAccessList = List[AccountAccess, MAX_ACCOUNTS]# Pre-block nonce structuresclass AccountNonce(Container):address: Address # account addressnonce_before: Nonce # nonce value before block executionNonceDiffs = List[AccountNonce, MAX_TXS]</code></pre>The structure is the same as in the access version, with <code>StorageValue</code> added to represent the value after the last access by each transaction.<ul><li>Exclude <code>SlotAccess.accesses</code> for reads: empty <code>SlotAccess.accesses</code> indicates a read.<ul><li>This means that only write operations consist of <code>(StorageKey, List[TxIndex], StorageValue)</code> tuples, significantly reducing the object’s size.</li></ul></li><li>Instead of post-execution values, we could include pre-execution values for reads and writes for each transaction. Thereby, EVM execution would not have to wait for disk reads. This is a completely separate design, coming with its own trade-offs, reducing execution time to <code>max(parallel IO, parallel EVM)</code>.</li></ul><blockquote>For syncing (c.f. healing phase), having state diffs (thus, the post-tx values) for writes is required for catching up with the chain while updating state. Instead of receiving new state values directly with their proofs, we can heal state using the state diffs inside blocks and verify the correctness of the process by comparing the final derived state root to the head block’s state root received from a light node (h/t dankrad).</blockquote>For contract deployments, the <code>code</code> must contain the runtime bytecode of the newly deployed contract.The <code>NonceDiffs</code> structure MUST record the pre-transaction nonce values for all <code>CREATE</code> and <code>CREATE2</code> deployer accounts and the deployed contracts in the block.An example BAL for block <code>21_935_797</code> might look like this:<pre><div><button></button><button></button></div><code>[('0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',[('0xa63b...c2',[0],'0x...'),('0x8b3e...a7',[0],'0x...'),('0xfb19...a8',[1, 2, 3, 4, 84, 85, 91],'0x...'),...])]</code></pre><hr>Balance diffs are needed to correctly handle execution that depends on an account’s balance. These diffs include every address touched by a transaction involving value transfers, along with the balance deltas, transaction senders, recipients, and the block’s coinbase.<pre><div><button></button><button></button></div><code># Type aliasesAddress = ByteVector(20)TxIndex = uint64BalanceDelta = ByteVector(12) # signed, two's complement encoding# ConstantsMAX_TXS = 30_000MAX_ACCOUNTS = 70_000 # 630m / 9300 (cost call to non-empty acc with value)# Containersclass BalanceChange(Container):tx_index: TxIndexdelta: BalanceDelta # signed integer, encoded as 12-byte vectorclass AccountBalanceDiff(Container):address: Addresschanges: List[BalanceChange, MAX_TXS]BalanceDiffs = List[AccountBalanceDiff, MAX_ACCOUNTS]</code></pre><ul><li>Deduplicated per address.</li><li>Each tuple lists the exact balance change for every relevant transaction.</li></ul>Example:<pre><div><button></button><button></button></div><code>[('0xdead...beef',[(0, -1000000000000000000), # tx 0: sent 1 ETH(2, +500000000000000000) # tx 2: received 0.5 ETH]),# ... additional entries]</code></pre><h1><a href="https://ethresear.ch#p-54283-state-bals-5" rel="nofollow"></a>State BALs</h1>This structure fully decouples execution from state, allowing validators to bypass any disk or trie lookups during execution, relying solely on the data provided in the block. The <code>pre_accesses</code> list provides the initial values of all accessed slots before the block starts, while <code>tx_accesses</code> traces the per-transaction access patterns and post-access values, enabling fine-grained parallel execution and verification.<ul><li>Larger in size</li><li>Execution time is <code>max(parallel IO, parallel EVM)</code>.</li></ul>An efficient SSZ object could look like the following:<pre><div><button></button><button></button></div><code># Type aliasesAddress = ByteVector(20)StorageKey = ByteVector(32)StorageValue = ByteVector(32)TxIndex = uint16# ConstantsMAX_TXS = 30_000MAX_SLOTS = 300_000MAX_ACCOUNTS = 300_000# Sub-containersclass PerTxAccess(Container):tx_index: TxIndexvalue_after: StorageValueclass SlotAccess(Container):slot: StorageKeyaccesses: List[PerTxAccess, MAX_TXS]class AccountAccess(Container):address: Addressaccesses: List[SlotAccess, MAX_SLOTS]class SlotPreValue(Container):slot: StorageKeyvalue_before: StorageValueclass AccountPreAccess(Container):address: Addressslots: List[SlotPreValue, MAX_SLOTS]# Unified top-level containerclass BlockAccessList(Container):pre_accesses: List[AccountPreAccess, MAX_ACCOUNTS]tx_accesses: List[AccountAccess, MAX_ACCOUNTS]</code></pre><blockquote>The balance and nonce diff remains the same. …</blockquote><h3><a href="https://ethresear.ch#p-54283-what-about-excluding-the-initial-read-values-6" rel="nofollow"></a>What about excluding the initial read values?</h3>Another variant of State BAL excludes read values, and only includes pre- and post-values for writes. In this model, <code>pre_accesses</code> and <code>tx_accesses</code> only contain storage slots that were written to, along with their corresponding <code>value_before</code> (from state) and <code>value_after</code> (from the transaction result).This reduces the size while still enabling full state reconstruction, as write slots define the only persistent changes. Read accesses are implicitly assumed to be resolved via traditional state lookups or cached on the client.<h1><a href="https://ethresear.ch#p-54283-worst-case-sizes-7" rel="nofollow"></a>Worst-Case Sizes</h1><h2><a href="https://ethresear.ch#p-54283-access-bal-8" rel="nofollow"></a>Access BAL</h2>The worst-case transaction consumes the entire block gas limit (36 million, as of April 2025) to access as many storage slots inside different contracts as possible by including them in the EIP-2930 access list.Thus, <code>(36_000_000 - 21_000) // 1900</code> gives us the max number of addresses (20 bytes) + storage keys (32 bytes) reads we can do, resulting in <code>18_947</code> storage reads and approximately 0.93 MiB.<blockquote>This is a pessimistic measure. It’s practically infeasible to use the block’s gas exclusively for SLOADs. With a custom contract (see <a href="https://github.com/nerolation/ethereum-stresser-contracts/blob/main/contracts/sload_stresser.sol" rel="nofollow">here</a>), I was able to trigger 16,646 SLOADs, not more. See <a href="https://dashboard.tenderly.co/tx/0x85bbcc2690fbf0ae9af5af1b3d4c006fd9804644695f095cba9e00ff09eaae8b" rel="nofollow">this example transaction on sepolia</a>.</blockquote>This is less than the current (and post-Prectra) worst-case block size achievable through calldata.<blockquote>Average BAL size sampled over 1,000 blocks between 21,605,993 and 2,223,0023 was around 57 KiB SSZ-encoded. On average, blocks in that time frame contained around 1,181 storage keys and 202 contracts per block.</blockquote><h2><a href="https://ethresear.ch#p-54283-execution-bals-9" rel="nofollow"></a>Execution BALs</h2>Including a 32-byte value per write entry doesn’t increase the worst-case BAL size. For reading <code>18_947</code> storage loads, it remains at 0.93 MiB.Worst-case balance diffs occur if a single transaction sends minimal value (1 wei) to multiple addresses:<ul><li>With the <code>21,000</code> base cost and <code>9,300</code> gas for calls, we get a maximum of 3,868 called addresses in one transaction (<code>(36_000_000-21_000)/9_300</code>). Including the <code>tx.from</code> and <code>tx.to</code> of that transaction + the block’s coinbase, we get <code>3,871</code> addresses. With 20-byte addresses and 12-byte balance deltas, we get a balance diff size of 0.12 MiB (12 bytes are enough to represent the total ETH supply).</li><li>Alternatively, using multiple transactions each sending 1 wei to a different account, we can theoretically pack 1,188 transactions into one block. With 3 addresses (<code>callee</code>, <code>tx.from</code> and <code>tx.to</code>) in the balance diff, and 12-byte deltas, we get 0.12 MiB in size.</li></ul><blockquote>A balance diff size sampled over 1,000 blocks (2,160,5993–2,223,0023) would have contained around 182 transactions and 250 addresses with balance deltas on average. This results in an average of 9.6 KiB, SSZ-encoded.</blockquote><h2><a href="https://ethresear.ch#p-54283-state-bals-10" rel="nofollow"></a>State BALs</h2>Including another 32 bytes for reads and writes increased the worst-case BAL size to around 1.51 MiB.<h1><a href="https://ethresear.ch#p-54283-comparison-of-different-designs-11" rel="nofollow"></a>Comparison of different designs</h1><div><a href="https://ethresear.ch/uploads/default/original/3X/a/f/af66c856b222706bd7ab1dcbbf34b088c78577b3.png" title="Screenshot from 2025-04-14 20-36-18" rel="nofollow"><img src="https://ethresear.ch/uploads/default/optimized/3X/a/f/af66c856b222706bd7ab1dcbbf34b088c78577b3_2_651x500.png" alt="Screenshot from 2025-04-14 20-36-18"><div>Screenshot from 2025-04-14 20-36-18904×694 102 KB</div></a></div>The current design specified in <a href="https://github.com/ethereum/EIPs/blob/master/EIPS/eip-7928.md" rel="nofollow">EIP-7928</a> adopts the Execution BAL model with post-tx values. This variant offers a compelling trade-off: it enables both I/O and EVM parallelism and includes sufficient state diffs for syncing, without the additional bandwidth costs associated with pre-transaction state snapshots.<h2><a href="https://ethresear.ch#p-54283-references-12" rel="nofollow"></a>References</h2><ul><li><a href="https://docs.google.com/document/d/1FoW_iuIPoYAjxy-AUGr_vRbIK_Zon3XDAb6heS_GWL0/edit?usp=sharing" rel="nofollow">ESP Academic Grant 2023: EthStorage/Quarkchain Earlier BAL Submission</a></li><li><a href="https://hackmd.io/X4Z4h-EQRPSiQF38rpN9aQ?view" rel="nofollow">Initial tests and simulations by EthStorage/Quarkchain</a></li><li><a href="https://www.scs.stanford.edu/24sp-cs244b/projects/Concerto_Transaction_Parallel_EVM.pdf" rel="nofollow">https://www.scs.stanford.edu/24sp-cs244b/projects/Concerto_Transaction_Parallel_EVM.pdf</a></li><li><a href="https://www.microsoft.com/en-us/research/wp-content/uploads/2021/09/3477132.3483564.pdf" rel="nofollow">https://www.microsoft.com/en-us/research/wp-content/uploads/2021/09/3477132.3483564.pdf</a></li><li><a href="https://writings.flashbots.net/speeding-up-evm-part-1" rel="nofollow">Speeding up the EVM (part 1) | Flashbots Writings</a></li></ul><div> </div></div>

Block-level Access Lists (BALs)

塊級訪問列表（BALs）
非常感謝Francesco、Jochem、V神、Ignacio、Gary、Dankrad、Carl、Ansgar和Tim的反饋和審閱。
bal_preview
總結：區塊構建者包含訪問列表...

<div><h1><a href="https://ethresear.ch#p-54283-block-level-access-lists-bals-1" rel="nofollow"></a>塊級訪問列表（BALs）</h1><blockquote>非常感謝 <a href="https://x.com/fradamt" rel="nofollow">弗朗西斯科</a>、<a href="https://x.com/JochemBrouwer96" rel="nofollow">約瑟姆</a>、<a href="https://x.com/VitalikButerin" rel="nofollow">V神</a>、<a href="https://x.com/ignaciohagopian" rel="nofollow">伊格納西奧</a>、<a href="https://x.com/gary_rong" rel="nofollow">加里</a>、<a href="https://x.com/dankrad" rel="nofollow">丹克拉德</a>、<a href="https://x.com/CarlBeek" rel="nofollow">卡爾</a>、<a href="https://x.com/adietrichs" rel="nofollow">安斯加爾</a>和<a href="https://x.com/TimBeiko" rel="nofollow">蒂姆</a>的反饋和審查。</blockquote><pre><div><button></button><button></button></div><code># 類型別名地址 = 位元組向量（20）交易索引 = 無符號整數64餘額變化 = 位元組向量（12） # 有符號，二進位制補碼編碼# 常量最大交易數 = 30_000最大賬戶數 = 70_000 # 630m / 9300（對非空賬戶帶值呼叫的成本）# 容器類 餘額變化（容器）:交易索引: 交易索引增量: 餘額變化 # 有符號整數，編碼為12位元組向量類 賬戶餘額差（容器）:地址: 地址變化: 列表[餘額變化, 最大交易數]餘額差 = 列表[賬戶餘額差, 最大賬戶數]</code></pre><ul><li>按地址去重。</li><li>每個元組列出每個相關交易的精確餘額變化。</li></ul>示例：<pre><div><button></button><button></button></div><code>[('0xdead...beef',[(0, -1000000000000000000), # 交易0：傳送1個以太幣(2, +500000000000000000) # 交易2：收到0.5個以太幣]),# ... 其他條目]</code></pre>

[後續內容保持不變，僅展示開頭部分的翻譯]

塊級訪問列表 (BAL)

一位加密貨幣分析師表示，加密貨幣交易員在社交媒體上尚未表現出足夠的恐慌情緒，不足以確認市場觸底。他認為比特幣仍有可能跌至 75,000 美元左右。

“這看起來很誘人……”

桑蒂門特：加密貨幣市場“還沒到恐慌的地步”，現在斷定底部尚未到來。

作者 | 十四君
1. 前言
一轉眼，筆者已然在 wallet 賽道里耕耘 4 年了。很多人覺得 2025 年的錢包賽道已經固化，但事實並非如此 — — 它正在暗流湧動，這一年裡：
· Coinbase 新發布 CDP 錢包，底層基於 TEE 技術構建；
· Binance 的 MPC 錢包，將密鑰分片託管引入 TEE 環境；
· Bitget 上週剛發佈社交登錄功能，底層由 TEE 託管；
· ...

簡述區塊鏈錢包歷史與 2025 市場格局

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