L2 block verification in assertion - enhance to use storageProofs

[johnwhitton]

Overview

Thanks for your work here and excellent tutorials.
We are looking to create a storageProof showing that the Arbitrum block.number for a Node is valid.
This is similar to the l2-block-verification-in-assertion tutorial

However instead of relying on event messaging we need to prove the underlying values on chain using a secureMerkleTrie.

We were hoping that the Arbitrum block.number or block.hash would be stored against the node.
However it appears that instead the closest we have is stateHash using the following values,

• assertion.afterstate.bytes32[0]: Arbitrum Block Number 0x17304244fc1e89f12d4a8b9f9dccac8f856f492babc0cc2b573b4bad73bfab41`
• assertion.afterstate.bytes32[1]: sendRoot 0x7a10019bc1e5caefe0e2ff1d63bf82fcc1b96a08b488d49d7a52ea057890c73e`
• assertion.u64vals[0]: InboxPosition 653147
• assertion.u64.vals[1]: PositionInMessage: 235
• assertion.machineStatus: Finished 1
• memoryFrame.currentInboxSize: numBlocks 14375

Question

Can you help us provide information as to where we can source the following fields

• `assertion.afterstate.bytes32[0]: Arbitrum Block Number
• `assertion.afterstate.bytes32[1]: sendRoot
• assertion.u64vals[0]: InboxPosition
• assertion.u64.vals[1]: PositionInMessage:
• assertion.machineStatus: Finished `
• memoryFrame.currentInboxSize: numBlocks

Or suggest an alternate approach to generating a storageProof linking the Node to it's Arbitrum Block Number.

Additional information

Sample data taken from this tenderly transaction

assertion = {
  "beforeState":{
    "globalState":{
        "bytes32Vals":["0xd9bab719a5f76ab63cf812bdf2f5a4be0d02b4ace8e4d92f18046c3f2912f5c5",
"0xa93a9bf66a781d701ff647c4786c0972dc4b4423fe8215b96c0962d9cc35567c"],
"u64Vals":653111,0]
  },
  "machineStatus":1
},
"afterState":{"globalState":{
  "bytes32Vals":
    ["0x17304244fc1e89f12d4a8b9f9dccac8f856f492babc0cc2b573b4bad73bfab41",
    "0x7a10019bc1e5caefe0e2ff1d63bf82fcc1b96a08b488d49d7a52ea057890c73e"],
  "u64Vals":[653147,235]
  },
  "machineStatus":1},
"numBlocks":14375},
 expectedNodeHash = 0x7572df8afe056a39e1e4b97552809ad508ebf45b4e89c85a115b43fd6aedbf8b, prevNodeInboxMaxCount = 653111)

which are calculated in createNewNode using the following logic

            memoryFrame.node = NodeLib.createNode(
                RollupLib.stateHash(assertion.afterState, memoryFrame.currentInboxSize),
                RollupLib.challengeRootHash(
                    memoryFrame.executionHash,
                    block.number,
                    wasmModuleRoot
                ),
                RollupLib.confirmHash(assertion),
                prevNodeNum,
                memoryFrame.deadlineBlock,
                newNodeHash
            );

Which calls

  function stateHash(ExecutionState calldata execState, uint256 inboxMaxCount)
        internal
        pure
        returns (bytes32)
    {
        return
            keccak256(
                abi.encodePacked(
                    execState.globalState.hash(),
                    inboxMaxCount,
                    execState.machineStatus
                )
            );
    }

This means in order to prove this storageSlot we will need to manually calculate the stateHash using all the input values from the Assertion. Specifically we need

struct Assertion {
    ExecutionState beforeState;
    ExecutionState afterState;
    uint64 numBlocks;
}

which uses

struct ExecutionState {
    GlobalState globalState;
    MachineStatus machineStatus;
}

and

struct GlobalState {
    bytes32[2] bytes32Vals;
    uint64[2] u64Vals;
}

and

enum MachineStatus {
    RUNNING,
    FINISHED,
    ERRORED,
    TOO_FAR
}

Arbitrum Rollup Admin Storage

Following is the storage for the proxied implementation contract from Sepolia.

To retrieve this use the command
cast storage 0x2Bd2fB395888B799f736E10728dA5C46b83B87Cf --rpc-url https://eth-sepolia.g.alchemy.com/v2/<alchemky-key> -e <etherscan-key>

Name	Type	Slot	Offset	Bytes	Value	Hex Value	Contract
_initialized	bool	0	0	1	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_initializing	bool	0	1	1	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
__gap	uint256[50]	1	0	1600	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_paused	bool	51	0	1	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
__gap	uint256[49]	52	0	1568	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
confirmPeriodBlocks	uint64	101	0	8	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
extraChallengeTimeBlocks	uint64	101	8	8	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
chainId	uint256	102	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
baseStake	uint256	103	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
wasmModuleRoot	bytes32	104	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
inbox	contract IInbox	105	0	20	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
bridge	contract IBridge	106	0	20	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
outbox	contract IOutbox	107	0	20	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
sequencerInbox	contract ISequencerInbox	108	0	20	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
rollupEventInbox	contract IRollupEventInbox	109	0	20	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
challengeManager	contract IChallengeManager	110	0	20	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
validatorUtils	address	111	0	20	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
validatorWalletCreator	address	112	0	20	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
loserStakeEscrow	address	113	0	20	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
stakeToken	address	114	0	20	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
minimumAssertionPeriod	uint256	115	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
isValidator	mapping(address => bool)	116	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_latestConfirmed	uint64	117	0	8	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_firstUnresolvedNode	uint64	117	8	8	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_latestNodeCreated	uint64	117	16	8	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_lastStakeBlock	uint64	117	24	8	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_nodes	mapping(uint64 => struct Node)	118	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_nodeStakers	mapping(uint64 => mapping(address => bool))	119	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_stakerList	address[]	120	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_stakerMap	mapping(address => struct IRollupCore.Staker)	121	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_zombies	struct RollupCore.Zombie[]	122	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_withdrawableFunds	mapping(address => uint256)	123	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
totalWithdrawableFunds	uint256	124	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
rollupDeploymentBlock	uint256	125	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
validatorWhitelistDisabled	bool	126	0	1	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic
_nodeCreatedAtArbSysBlock	mapping(uint64 => uint256)	127	0	32	0	0x0000000000000000000000000000000000000000000000000000000000000000	src/rollup/RollupAdminLogic.sol:RollupAdminLogic

[johnwhitton]

Any update on this?

[Jason-W123]

Hey, do you need to prove block number or block hash?
If, just block hash, you can get assertion, it related inboxMsgCount and the node number off chain, then upload them on chain via this contract interface example:

function verify(Assertion calldata assertion, uint256 inboxMsgCount, uint256 nodeNumber) public returns(bool){}

You can implement this method by:

1. Get node from the rollup contract by nodeNumber.
2. Hash assertion and inboxMsgCount. You can use RollupLib to do this: https://github.com/OffchainLabs/nitro-contracts/blob/main/src/rollup/RollupLib.sol#L21
3. Then compare the statehash of the node you got from step one with the result from the step 2.

If you want to verify the block number, you can translate inboxMsgCount to the l2 block number by add the l2 genesis number, currently arb1 is 22207817 but note the translation between inboxMsgCount and l2 block number might be changed in the future.

Also the roots on outbox contains blockhash: https://github.com/OffchainLabs/nitro-contracts/blob/main/src/bridge/AbsOutbox.sol#L105