First draft of changes

contracts/optimistic-ethereum/OVM/bridge/messaging/OVM_L1CrossDomainMessenger.sol

@@ -287,7 +287,8 @@ contract OVM_L1CrossDomainMessenger is iOVM_L1CrossDomainMessenger, Abs_BaseCros
         iOVM_CanonicalTransactionChain(resolve("OVM_CanonicalTransactionChain")).enqueue(
             resolve("OVM_L2CrossDomainMessenger"),
             _gasLimit,
-            _message
+            _message,
+            0, ""
         );
     }
 }

contracts/optimistic-ethereum/OVM/chain/OVM_CanonicalTransactionChain.sol

@@ -8,6 +8,7 @@ import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
 import { Lib_AddressResolver } from "../../libraries/resolver/Lib_AddressResolver.sol";
 import { Lib_MerkleTree } from "../../libraries/utils/Lib_MerkleTree.sol";
 import { Lib_Math } from "../../libraries/utils/Lib_Math.sol";
+import { ReplayProtection } from "../../libraries/standards/ReplayProtection.sol";
 
 /* Interface Imports */
 import { iOVM_CanonicalTransactionChain } from "../../iOVM/chain/iOVM_CanonicalTransactionChain.sol";
@@ -30,7 +31,7 @@ import { OVM_ExecutionManager } from "../execution/OVM_ExecutionManager.sol";
  * Compiler used: solc
  * Runtime target: EVM
  */
-contract OVM_CanonicalTransactionChain is iOVM_CanonicalTransactionChain, Lib_AddressResolver {
+contract OVM_CanonicalTransactionChain is iOVM_CanonicalTransactionChain, Lib_AddressResolver, ReplayProtection {
 
     /*************
      * Constants *
@@ -263,16 +264,21 @@ contract OVM_CanonicalTransactionChain is iOVM_CanonicalTransactionChain, Lib_Ad
         return uint40(queue().length() / 2);
     }
 
+
     /**
      * Adds a transaction to the queue.
      * @param _target Target L2 contract to send the transaction to.
      * @param _gasLimit Gas limit for the enqueued L2 transaction.
      * @param _data Transaction data.
+     * @param _nonce Replay protection nonce
+     * @param _signature Signature
      */
     function enqueue(
         address _target,
         uint256 _gasLimit,
-        bytes memory _data
+        bytes memory _data,
+        uint _nonce,
+        bytes memory _signature
     )
         override
         public
@@ -312,9 +318,18 @@ contract OVM_CanonicalTransactionChain is iOVM_CanonicalTransactionChain, Lib_Ad
             i++;
         }
 
+        address signer;
+        if(_signature.length != 0) {
+            // Extract signer's address.
+            bytes32 message = keccak256(abi.encode("enqueue", _target, _gasLimit, _data, address(this), _nonce));
+            signer = checkSignatureAndReplayProtection(message, _nonce, _signature); // Throws if signature or replay protection is invalid
+        } else {
+            signer = msg.sender;
+        }
+
         bytes32 transactionHash = keccak256(
             abi.encode(
-                msg.sender,
+                signer,
                 _target,
                 _gasLimit,
                 _data
@@ -336,7 +351,7 @@ contract OVM_CanonicalTransactionChain is iOVM_CanonicalTransactionChain, Lib_Ad
 
         uint256 queueIndex = queue.length() / 2;
         emit TransactionEnqueued(
-            msg.sender,
+            signer,
             _target,
             _gasLimit,
             _data,
@@ -348,9 +363,13 @@ contract OVM_CanonicalTransactionChain is iOVM_CanonicalTransactionChain, Lib_Ad
     /**
      * Appends a given number of queued transactions as a single batch.
      * @param _numQueuedTransactions Number of transactions to append.
+     * @param _nonce Replay protection nonce
+     * @param _signature Signature
      */
     function appendQueueBatch(
-        uint256 _numQueuedTransactions
+        uint256 _numQueuedTransactions,
+        uint _nonce,
+        bytes memory _signature
     )
         override
         public
@@ -364,11 +383,20 @@ contract OVM_CanonicalTransactionChain is iOVM_CanonicalTransactionChain, Lib_Ad
             "Must append more than zero transactions."
         );
 
+        address signer;
+        if(_signature.length != 0) {
+            // Extract signer's address.
+            bytes32 message = keccak256(abi.encode("appendQueueBatch", _numQueuedTransactions, address(this), _nonce));
+            signer = checkSignatureAndReplayProtection(message, _nonce, _signature); // Throws if signature or replay protection is invalid
+        } else {
+            signer = msg.sender;
+        }
+
         bytes32[] memory leaves = new bytes32[](_numQueuedTransactions);
         uint40 nextQueueIndex = getNextQueueIndex();
 
         for (uint256 i = 0; i < _numQueuedTransactions; i++) {
-            if (msg.sender != resolve("OVM_Sequencer")) {
+            if (signer != resolve("OVM_Sequencer")) {
                 Lib_OVMCodec.QueueElement memory el = getQueueElement(nextQueueIndex);
                 require(
                     el.timestamp + forceInclusionPeriodSeconds < block.timestamp,
@@ -422,8 +450,17 @@ contract OVM_CanonicalTransactionChain is iOVM_CanonicalTransactionChain, Lib_Ad
             "Actual batch start index does not match expected start index."
         );
 
+        address signer = msg.sender;
+        // if(_signature.length == 0) {
+        //     // Extract signer's address.
+        //     bytes32 message = keccak256(abi.encode("appendSequencerBatch", address(this), _nonce));
+        //     signer = checkSignatureAndReplayProtection(message, _nonce, _signature); // Throws if signature or replay protection is invalid
+        // } else {
+        //     signer = msg.sender;
+        // }
+
         require(
-            msg.sender == resolve("OVM_Sequencer"),
+            signer == resolve("OVM_Sequencer"),
             "Function can only be called by the Sequencer."
         );
 

contracts/optimistic-ethereum/OVM/chain/OVM_StateCommitmentChain.sol

@@ -6,6 +6,7 @@ pragma experimental ABIEncoderV2;
 import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
 import { Lib_AddressResolver } from "../../libraries/resolver/Lib_AddressResolver.sol";
 import { Lib_MerkleTree } from "../../libraries/utils/Lib_MerkleTree.sol";
+import { ReplayProtection } from "../../libraries/standards/ReplayProtection.sol";
 
 /* Interface Imports */
 import { iOVM_FraudVerifier } from "../../iOVM/verification/iOVM_FraudVerifier.sol";
@@ -27,7 +28,7 @@ import '@openzeppelin/contracts/math/SafeMath.sol';
  * Compiler used: solc
  * Runtime target: EVM
  */
-contract OVM_StateCommitmentChain is iOVM_StateCommitmentChain, Lib_AddressResolver {
+contract OVM_StateCommitmentChain is iOVM_StateCommitmentChain, Lib_AddressResolver, ReplayProtection {
 
     /*************
      * Constants *
@@ -126,7 +127,9 @@ contract OVM_StateCommitmentChain is iOVM_StateCommitmentChain, Lib_AddressResol
      */
     function appendStateBatch(
         bytes32[] memory _batch,
-        uint256 _shouldStartAtElement
+        uint256 _shouldStartAtElement,
+        uint _nonce,
+        bytes memory _signature
     )
         override
         public
@@ -138,9 +141,18 @@ contract OVM_StateCommitmentChain is iOVM_StateCommitmentChain, Lib_AddressResol
             "Actual batch start index does not match expected start index."
         );
 
+        address signer;
+        if(_signature.length != 0) {
+            // Extract signer's address.
+            bytes32 message = keccak256(abi.encode("appendStateBatch", _batch, _shouldStartAtElement, address(this), _nonce));
+            signer = checkSignatureAndReplayProtection(message, _nonce, _signature); // Throws if signature or replay protection is invalid
+        } else {
+            signer = msg.sender;
+        }
+
         // Proposers must have previously staked at the BondManager
         require(
-            iOVM_BondManager(resolve("OVM_BondManager")).isCollateralized(msg.sender),
+            iOVM_BondManager(resolve("OVM_BondManager")).isCollateralized(signer),
             "Proposer does not have enough collateral posted"
         );
 
@@ -158,21 +170,34 @@ contract OVM_StateCommitmentChain is iOVM_StateCommitmentChain, Lib_AddressResol
         // to be used in the fraud proofs
         _appendBatch(
             _batch,
-            abi.encode(block.timestamp, msg.sender)
+            abi.encode(block.timestamp, signer),
+            signer
         );
     }
 
     /**
      * @inheritdoc iOVM_StateCommitmentChain
      */
     function deleteStateBatch(
-        Lib_OVMCodec.ChainBatchHeader memory _batchHeader
+        Lib_OVMCodec.ChainBatchHeader memory _batchHeader, 
+        uint _nonce, 
+        bytes memory _signature
     )
         override
         public
     {
+
+        address signer;
+        if(_signature.length != 0) {
+            // Extract signer's address.
+            bytes32 message = keccak256(abi.encode("deleteStateBatch", _batchHeader, address(this), _nonce));
+            signer = checkSignatureAndReplayProtection(message, _nonce, _signature); // Throws if signature or replay protection is invalid
+        } else {
+            signer = msg.sender;
+        }
+
         require(
-            msg.sender == resolve("OVM_FraudVerifier"),
+            signer == resolve("OVM_FraudVerifier"),
             "State batches can only be deleted by the OVM_FraudVerifier."
         );
 
@@ -312,17 +337,19 @@ contract OVM_StateCommitmentChain is iOVM_StateCommitmentChain, Lib_AddressResol
      * Appends a batch to the chain.
      * @param _batch Elements within the batch.
      * @param _extraData Any extra data to append to the batch.
+     * @param _signer Signer's address (verified in parent call).
      */
     function _appendBatch(
         bytes32[] memory _batch,
-        bytes memory _extraData
+        bytes memory _extraData,
+        address _signer
     )
         internal
     {
         address sequencer = resolve("OVM_Sequencer");
         (uint40 totalElements, uint40 lastSequencerTimestamp) = _getBatchExtraData();
 
-        if (msg.sender == sequencer) {
+        if (_signer == sequencer) {
             lastSequencerTimestamp = uint40(block.timestamp);
         } else {
             // We keep track of the last batch submitted by the sequencer so there's a window in

contracts/optimistic-ethereum/OVM/verification/OVM_FraudVerifier.sol

@@ -282,7 +282,7 @@ contract OVM_FraudVerifier is Lib_AddressResolver, Abs_FraudContributor, iOVM_Fr
 
         // Delete the state batch.
         ovmStateCommitmentChain.deleteStateBatch(
-            _postStateRootBatchHeader
+            _postStateRootBatchHeader, 0, ""
         );
 
         // Get the timestamp and publisher for that block.

contracts/optimistic-ethereum/iOVM/chain/iOVM_CanonicalTransactionChain.sol

@@ -184,20 +184,28 @@ interface iOVM_CanonicalTransactionChain {
      * @param _target Target contract to send the transaction to.
      * @param _gasLimit Gas limit for the given transaction.
      * @param _data Transaction data.
+     * @param _nonce Replay protection nonce.
+     * @param _signature Signature.
      */
     function enqueue(
         address _target,
         uint256 _gasLimit,
-        bytes memory _data
+        bytes memory _data,
+        uint _nonce,
+        bytes memory _signature
     )
         external;
 
     /**
      * Appends a given number of queued transactions as a single batch.
      * @param _numQueuedTransactions Number of transactions to append.
+     * @param _nonce Replay protection nonce.
+     * @param _signature Signature.
      */
     function appendQueueBatch(
-        uint256 _numQueuedTransactions
+        uint256 _numQueuedTransactions,
+        uint _nonce,
+        bytes memory _signature
     )
         external;
 

contracts/optimistic-ethereum/iOVM/chain/iOVM_StateCommitmentChain.sol

@@ -69,19 +69,27 @@ interface iOVM_StateCommitmentChain {
      * Appends a batch of state roots to the chain.
      * @param _batch Batch of state roots.
      * @param _shouldStartAtElement Index of the element at which this batch should start.
+     * @param _nonce Replay protection nonce.
+     * @param _signature Signature.
      */
     function appendStateBatch(
         bytes32[] calldata _batch,
-        uint256 _shouldStartAtElement
+        uint256 _shouldStartAtElement,         
+        uint _nonce,
+        bytes memory _signature
     )
         external;
 
     /**
      * Deletes all state roots after (and including) a given batch.
      * @param _batchHeader Header of the batch to start deleting from.
+     * @param _nonce Replay protection nonce.
+     * @param _signature Signature.
      */
     function deleteStateBatch(
-        Lib_OVMCodec.ChainBatchHeader memory _batchHeader
+        Lib_OVMCodec.ChainBatchHeader memory _batchHeader,
+        uint _nonce,
+        bytes memory _signature
     )
         external;
 

contracts/optimistic-ethereum/libraries/standards/ReplayProtection.sol

@@ -0,0 +1,29 @@
+pragma solidity >=0.5.16 <0.8.0;
+
+/* External Imports */
+import "@openzeppelin/contracts/cryptography/ECDSA.sol";
+
+contract ReplayProtection {
+
+    /*********************
+     * Replay protection *
+     ********************/
+    mapping(address => uint) nonce;
+
+    /**
+     * Throws if the replay protection is incorrect for the signer. 
+     * It will check that the submitted nonce is greater than the nonce stored. Unlike Ethereum which requires it
+     * to strictly increment by 1.
+     * 
+     * @param _hash Hash of message to be signed.
+     * @param _nonce Replay protection nonce.
+     * @param _signature Signature to verify.
+     * @return Signer's address.
+     */
+    function checkSignatureAndReplayProtection(bytes32 _hash, uint _nonce, bytes memory _signature) internal returns(address) {
+        address signer = ECDSA.recover(_hash, _signature);
+        require(_nonce > nonce[signer], "Transaction already submitted by signer");
+        nonce[signer] = _nonce; // Re-use storage to minimise gas cost 
+        return signer;
+    }
+}

hardhat.config.ts

@@ -29,7 +29,7 @@ const config: HardhatUserConfig = {
     },
   },
   typechain: {
-    outDir: 'build/types',
+    outDir: 'src/types',
     target: 'ethers-v5',
   },
 }

test/contracts/OVM/bridge/base/OVM_L1CrossDomainMessenger.spec.ts

@@ -109,12 +109,19 @@ describe('OVM_L1CrossDomainMessenger', () => {
         OVM_L1CrossDomainMessenger.sendMessage(target, message, gasLimit)
       ).to.not.be.reverted
 
+      console.log(
+        JSON.stringify(
+          Mock__OVM_CanonicalTransactionChain.smocked.enqueue.calls[0]
+        )
+      )
       expect(
         Mock__OVM_CanonicalTransactionChain.smocked.enqueue.calls[0]
       ).to.deep.equal([
         Mock__OVM_L2CrossDomainMessenger.address,
         BigNumber.from(gasLimit),
         getXDomainCalldata(await signer.getAddress(), target, message, 0),
+        BigNumber.from('0'),
+        '0x',
       ])
     })