Merge pull request #27 from NethermindEth/anshu/task-manager-preconfi…

…rmation-challenge

Add preconfirmation challenge

.gitmodules

@@ -7,3 +7,6 @@
 [submodule "SmartContracts/lib/openzeppelin-contracts-upgradeable"]
 	path = SmartContracts/lib/openzeppelin-contracts-upgradeable
 	url = https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable
+[submodule "SmartContracts/lib/openzeppelin-contracts"]
+	path = SmartContracts/lib/openzeppelin-contracts
+	url = https://github.com/OpenZeppelin/openzeppelin-contracts

SmartContracts/remappings.txt

@@ -1,3 +1,4 @@
 eigenlayer-middleware/=lib/eigenlayer-middleware/src
 forge-std/=lib/forge-std/src/
 openzeppelin-contracts-upgradeable/=lib/openzeppelin-contracts-upgradeable/contracts
+openzeppelin-contracts/=lib/openzeppelin-contracts/contracts

SmartContracts/src/avs/PreconfTaskManager.sol

@@ -6,6 +6,7 @@ import {IPreconfTaskManager} from "../interfaces/IPreconfTaskManager.sol";
 import {IPreconfServiceManager} from "../interfaces/IPreconfServiceManager.sol";
 import {IRegistryCoordinator} from "eigenlayer-middleware/interfaces/IRegistryCoordinator.sol";
 import {IIndexRegistry} from "eigenlayer-middleware/interfaces/IIndexRegistry.sol";
+import {ECDSA} from "openzeppelin-contracts/utils/cryptography/ECDSA.sol";
 
 contract PreconfTaskManager is IPreconfTaskManager {
     IPreconfServiceManager internal immutable preconfServiceManager;
@@ -131,7 +132,38 @@ contract PreconfTaskManager is IPreconfTaskManager {
         taikoL1.proposeBlock{value: msg.value}(blockParams, txList);
     }
 
-    function proveIncorrectPreconfirmation(PreconfirmationHeader memory header, bytes memory signature) external {}
+    /**
+     * @notice Slashes an operator if their preconfirmation has not been respected onchain
+     * @dev The ECDSA signature expected by this function must be from a library that prevents malleable
+     * signatures i.e `s` value is in the lower half order, and the `v` value is either 27 or 28.
+     * @param header The header of the preconfirmation sent to the AVS P2P
+     * @param signature ECDSA-signed hash of the preconfirmation header
+     */
+    function proveIncorrectPreconfirmation(PreconfirmationHeader calldata header, bytes calldata signature) external {
+        IPreconfTaskManager.ProposedBlock memory proposedBlock = proposedBlocks[header.blockId];
+
+        if (block.timestamp - proposedBlock.timestamp >= DISPUTE_PERIOD) {
+            // Revert if the dispute window has been missed
+            revert IPreconfTaskManager.MissedDisputeWindow();
+        } else if (header.chainId != block.chainid) {
+            // Revert if the preconfirmation was provided on another chain
+            revert IPreconfTaskManager.PreconfirmationChainIdMismatch();
+        }
+
+        bytes32 headerHash = keccak256(abi.encodePacked(header.blockId, header.chainId, header.txListHash));
+        address preconfSigner = ECDSA.recover(headerHash, signature);
+
+        // Note: It is not required to verify that the preconfSigner is a valid operator. That is implicitly
+        // verified by EL.
+
+        // Slash if the preconfirmation was given offchain, but block proposal was missed OR
+        // the preconfirmed set of transactions is different from the transactions in the proposed block.
+        if (preconfSigner != proposedBlock.proposer || header.txListHash != proposedBlock.txListHash) {
+            preconfServiceManager.slashOperator(preconfSigner);
+        } else {
+            revert IPreconfTaskManager.PreconfirmationIsCorrect();
+        }
+    }
 
     function proveIncorrectLookahead(
         uint256 offset,

SmartContracts/src/interfaces/IPreconfTaskManager.sol

@@ -51,6 +51,12 @@ interface IPreconfTaskManager {
     error SenderNotRegisteredInAVS();
     /// @dev The timestamp in the lookahead is not of a valid future slot in the present epoch
     error InvalidSlotTimestamp();
+    /// @dev The chain id on which the preconfirmation was signed is different from the current chain's id
+    error PreconfirmationChainIdMismatch();
+    /// @dev The dispute window for proving incorretc lookahead or preconfirmation is over
+    error MissedDisputeWindow();
+    /// @dev The disputed preconfirmation is correct
+    error PreconfirmationIsCorrect();
 
     /// @dev Accepts block proposal by an operator and forwards it to TaikoL1 contract
     function newBlockProposal(