add timestamp check to the invite commitments

packages/contracts-periphery/contracts/foundry-tests/OptimistInviter.t.sol

@@ -83,6 +83,10 @@ contract OptimistInviter_Initializer is Test {
         optimistInviterHelper = new OptimistInviterHelper(optimistInviter, "OptimistInviter");
     }
 
+    function _passMinCommitmentPeriod() internal {
+        vm.warp(optimistInviter.MIN_COMMITMENT_PERIOD() + block.timestamp);
+    }
+
     /**
      * @notice Returns a user's current invite count, as stored in the AttestationStation.
      */
@@ -174,7 +178,7 @@ contract OptimistInviter_Initializer is Test {
         optimistInviter.commitInvite(hashedSignature);
 
         // Check that the commitment was stored correctly
-        assertTrue(optimistInviter.commitments(hashedSignature));
+        assertEq(optimistInviter.commitmentTimestamps(hashedSignature), block.timestamp);
     }
 
     /**
@@ -196,7 +200,12 @@ contract OptimistInviter_Initializer is Test {
         _commitInviteAs(_claimer, signature);
 
         // The hash(claimer ++ signature) should be committed
-        assertEq(optimistInviter.commitments(keccak256(abi.encode(_claimer, signature))), true);
+        assertEq(
+            optimistInviter.commitmentTimestamps(keccak256(abi.encode(_claimer, signature))),
+            block.timestamp
+        );
+
+        _passMinCommitmentPeriod();
 
         // OptimistInviter should issue a new attestation allowing claimer to mint
         vm.expectEmit(true, true, true, true, address(attestationStation));
@@ -324,7 +333,7 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
         bytes32 hashedSignature = keccak256(abi.encode(sally, signature));
         optimistInviter.commitInvite(hashedSignature);
 
-        assertTrue(optimistInviter.commitments(hashedSignature));
+        assertEq(optimistInviter.commitmentTimestamps(hashedSignature), block.timestamp);
     }
 
     /**
@@ -338,7 +347,24 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
         bytes32 hashedSignature = keccak256(abi.encode(eve, signature));
         optimistInviter.commitInvite(hashedSignature);
 
-        assertTrue(optimistInviter.commitments(hashedSignature));
+        assertEq(optimistInviter.commitmentTimestamps(hashedSignature), block.timestamp);
+    }
+
+    /**
+     * @notice Attempting to commit the same hash twice should revert. This prevents griefing.
+     */
+    function test_commitInvite_committingSameHashTwice_reverts() external {
+        _grantInvitesTo(bob);
+        (, bytes memory signature) = _issueInviteAs(bobPrivateKey);
+
+        vm.prank(sally);
+        bytes32 hashedSignature = keccak256(abi.encode(eve, signature));
+        optimistInviter.commitInvite(hashedSignature);
+
+        assertEq(optimistInviter.commitmentTimestamps(hashedSignature), block.timestamp);
+
+        vm.expectRevert("OptimistInviter: commitment already made");
+        optimistInviter.commitInvite(hashedSignature);
     }
 
     /**
@@ -360,10 +386,9 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
             bytes memory signature
         ) = _issueInviteAs(bobPrivateKey);
 
-        _commitInviteAs(sally, signature);
-
         vm.prank(ted);
         optimistInviter.commitInvite(keccak256(abi.encode(sally, signature)));
+        _passMinCommitmentPeriod();
 
         vm.expectEmit(true, true, true, true, address(attestationStation));
         emit AttestationCreated(
@@ -385,6 +410,23 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
         assertFalse(_hasMintAttestation(eve));
     }
 
+    function test_claimInvite_claimBeforeMinCommitmentPeriod_reverts() external {
+        _grantInvitesTo(bob);
+        (
+            OptimistInviter.ClaimableInvite memory claimableInvite,
+            bytes memory signature
+        ) = _issueInviteAs(bobPrivateKey);
+
+        _commitInviteAs(sally, signature);
+
+        // Some time passes, but not enough to meet the minimum commitment period
+        vm.warp(block.timestamp + 10);
+
+        vm.expectRevert("OptimistInviter: minimum commitment period has not elapsed yet");
+        vm.prank(sally);
+        optimistInviter.claimInvite(sally, claimableInvite, signature);
+    }
+
     /**
      * @notice Signature issued for previous versions of the contract should fail.
      */
@@ -402,6 +444,7 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
             );
 
         _commitInviteAs(sally, signature);
+        _passMinCommitmentPeriod();
 
         vm.expectRevert("OptimistInviter: invalid signature");
         vm.prank(sally);
@@ -426,6 +469,7 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
             );
 
         _commitInviteAs(sally, signature);
+        _passMinCommitmentPeriod();
 
         vm.expectRevert("OptimistInviter: invalid signature");
         vm.prank(sally);
@@ -450,6 +494,7 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
             );
 
         _commitInviteAs(sally, signature);
+        _passMinCommitmentPeriod();
 
         vm.expectRevert("OptimistInviter: invalid signature");
         vm.prank(sally);
@@ -468,13 +513,14 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
         ) = _issueThenClaimShouldSucceed(bobPrivateKey, sally);
 
         // Sally tries to claim the invite using the same signature
-        _commitInviteAs(sally, signature);
         vm.expectRevert("OptimistInviter: nonce has already been used");
         vm.prank(sally);
         optimistInviter.claimInvite(sally, claimableInvite, signature);
 
         // Carol tries to claim the invite using the same signature
         _commitInviteAs(carol, signature);
+        _passMinCommitmentPeriod();
+
         vm.expectRevert("OptimistInviter: nonce has already been used");
         vm.prank(carol);
         optimistInviter.claimInvite(carol, claimableInvite, signature);
@@ -498,6 +544,7 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
 
         // Sally tries to claim the invite
         _commitInviteAs(sally, signature);
+        _passMinCommitmentPeriod();
 
         vm.expectEmit(true, true, true, true, address(attestationStation));
         emit AttestationCreated(
@@ -543,6 +590,8 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
         _commitInviteAs(sally, bobSignature);
         _commitInviteAs(sally, carolSignature);
 
+        _passMinCommitmentPeriod();
+
         vm.expectRevert("OptimistInviter: invalid signature");
         vm.prank(sally);
         optimistInviter.claimInvite(sally, bobClaimableInvite, carolSignature);
@@ -560,6 +609,7 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
         ) = _issueInviteAs(bobPrivateKey);
 
         _commitInviteAs(sally, signature);
+        _passMinCommitmentPeriod();
 
         vm.expectRevert("OptimistInviter: issuer has no invites");
         vm.prank(sally);
@@ -588,6 +638,7 @@ contract OptimistInviterTest is OptimistInviter_Initializer {
         ) = _issueInviteAs(bobPrivateKey);
 
         _commitInviteAs(eve, signature4);
+        _passMinCommitmentPeriod();
 
         vm.expectRevert("OptimistInviter: issuer has no invites");
         vm.prank(eve);

packages/contracts-periphery/contracts/testing/helpers/OptimistInviterHelper.sol

@@ -10,16 +10,33 @@ import { OptimistInviter } from "../../universal/op-nft/OptimistInviter.sol";
  * Made this a separate contract instead of including in OptimistInviter.t.sol for reusability.
  */
 contract OptimistInviterHelper {
+    /**
+     * @notice EIP712 typehash for the ClaimableInvite type.
+     */
     bytes32 public constant CLAIMABLE_INVITE_TYPEHASH =
         keccak256("ClaimableInvite(address issuer,bytes32 nonce)");
 
+    /**
+     * @notice EIP712 typehash for the EIP712Domain type that is included as part of the signature.
+     */
     bytes32 public constant EIP712_DOMAIN_TYPEHASH =
         keccak256(
             "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
         );
 
+    /**
+     * @notice Address of OptimistInviter contract we are testing.
+     */
     OptimistInviter public optimistInviter;
+
+    /**
+     * @notice OptimistInviter contract name. Used to construct the EIP-712 domain.
+     */
     string public name;
+
+    /**
+     * @notice Keeps track of current nonce to generate new nonces for each invite.
+     */
     uint256 public currentNonce;
 
     constructor(OptimistInviter _optimistInviter, string memory _name) {
@@ -29,7 +46,11 @@ contract OptimistInviterHelper {
     }
 
     /**
-     * @notice Returns the hash of the struct ClaimableInvite
+     * @notice Returns the hash of the struct ClaimableInvite.
+     *
+     * @param _claimableInvite ClaimableInvite struct to hash.
+     *
+     * @return EIP-712 typed struct hash.
      */
     function getClaimableInviteStructHash(OptimistInviter.ClaimableInvite memory _claimableInvite)
         public
@@ -49,13 +70,19 @@ contract OptimistInviterHelper {
     /**
      * @notice Returns a bytes32 nonce that should change everytime. In practice, people should use
      *         pseudorandom nonces.
+     *
+     * @return Nonce that should be used as part of ClaimableInvite.
      */
     function consumeNonce() public returns (bytes32) {
         return bytes32(keccak256(abi.encode(currentNonce++)));
     }
 
     /**
-     * @notice Returns a ClaimableInvite with the issuer and current nonce
+     * @notice Returns a ClaimableInvite with the issuer and current nonce.
+     *
+     * @param _issuer Issuer to include in the ClaimableInvite.
+     *
+     * @return ClaimableInvite that can be hashed & signed.
      */
     function getClaimableInviteWithNewNonce(address _issuer)
         public
@@ -66,6 +93,10 @@ contract OptimistInviterHelper {
 
     /**
      * @notice Computes the EIP712 digest with default correct parameters.
+     *
+     * @param _claimableInvite ClaimableInvite struct to hash.
+     *
+     * @return EIP-712 compatible digest.
      */
     function getDigest(OptimistInviter.ClaimableInvite calldata _claimableInvite)
         public
@@ -85,6 +116,14 @@ contract OptimistInviterHelper {
     /**
      * @notice Computes the EIP712 digest with the given domain parameters.
      *         Used for testing that different domain parameters fail.
+     *
+     * @param _claimableInvite   ClaimableInvite struct to hash.
+     * @param _name              Contract name to use in the EIP712 domain.
+     * @param _version           Contract version to use in the EIP712 domain.
+     * @param _chainid           Chain ID to use in the EIP712 domain.
+     * @param _verifyingContract Address to use in the EIP712 domain.
+     *
+     * @return EIP-712 compatible digest.
      */
     function getDigestWithEIP712Domain(
         OptimistInviter.ClaimableInvite calldata _claimableInvite,

packages/contracts-periphery/contracts/universal/op-nft/OptimistInviter.sol

@@ -31,14 +31,15 @@ import {
  *           5) claimer commits the hash of the address they want to receive the invite on and the
  *              received signature keccak256(abi.encode(addressToReceiveTo, receivedSignature))
  *              using the commitInvite function
- *           6) claimer reveals the plaintext ClaimableInvite and the signature using the
+ *           6) claimer waits for the MIN_COMMITMENT_PERIOD to pass.
+ *           7) claimer reveals the plaintext ClaimableInvite and the signature using the
  *              claimInvite function, receiving the "optimist.can-mint-from-invite" attestation
  */
 contract OptimistInviter is Semver, EIP712Upgradeable {
     /**
      * @notice Emitted when an invite is claimed.
      *
-     * @param issuer Address that issued the signature.
+     * @param issuer  Address that issued the signature.
      * @param claimer Address that claimed the invite.
      */
     event InviteClaimed(address indexed issuer, address indexed claimer);
@@ -78,6 +79,18 @@ contract OptimistInviter is Semver, EIP712Upgradeable {
      */
     AttestationStation public immutable ATTESTATION_STATION;
 
+    /**
+     * @notice Minimum age of a commitment (in seconds) before it can be revealed using claimInvite.
+     *         Currently set to 60 seconds.
+     *
+     *         Prevents an attacker from front-running a commitment by taking the signature in the
+     *         claimInvite call and quickly committing and claiming it before the the claimer's
+     *         transaction succeeds. With this, frontrunning a commitment requires that an attacker
+     *         be able to prevent the honest claimer's claimInvite transaction from being included
+     *         for this long.
+     */
+    uint256 public constant MIN_COMMITMENT_PERIOD = 60;
+
     /**
      * @notice Struct that represents a claimable invite that will be signed by the issuer.
      *
@@ -94,9 +107,9 @@ contract OptimistInviter is Semver, EIP712Upgradeable {
     }
 
     /**
-     * @notice Maps from hashes to whether or not they have been committed.
+     * @notice Maps from hashes to the timestamp when they were committed.
      */
-    mapping(bytes32 => bool) public commitments;
+    mapping(bytes32 => uint256) public commitmentTimestamps;
 
     /**
      * @notice Maps from addresses to nonces to whether or not they have been used.
@@ -127,7 +140,7 @@ contract OptimistInviter is Semver, EIP712Upgradeable {
      *         claimed yet will no longer be accepted by the claimInvite function. Please make
      *         sure to notify the issuers that they must re-issue their invite signatures.
      *
-     * @param _name Contract name
+     * @param _name Contract name.
      */
     function initialize(string memory _name) public initializer {
         __EIP712_init(_name, EIP712_VERSION);
@@ -181,12 +194,21 @@ contract OptimistInviter is Semver, EIP712Upgradeable {
      *         scheme, anyone who is watching the mempool can take the signature being submitted
      *         and front run the transaction to claim the invite to their own address.
      *
+     *         The same commitment can only be made once, and the function reverts if the
+     *         commitment has already been made. This prevents griefing where a malicious party can
+     *         prevent the original claimer from being able to claimInvite.
+     *
      *
      * @param _commitment A hash of the claimer and signature concatenated.
      *                    keccak256(abi.encode(_claimer, _signature))
      */
     function commitInvite(bytes32 _commitment) public {
-        commitments[_commitment] = true;
+        // Check that the commitment hasn't already been made. This prevents griefing where
+        // a malicious party continuously re-submits the same commitment, preventing the original
+        // claimer from claiming their invite by resetting the minimum commitment period.
+        require(commitmentTimestamps[_commitment] == 0, "OptimistInviter: commitment already made");
+
+        commitmentTimestamps[_commitment] = block.timestamp;
     }
 
     /**
@@ -196,9 +218,10 @@ contract OptimistInviter is Semver, EIP712Upgradeable {
      *         committed using commitInvite. Before issuing the "optimist.can-mint-from-invite"
      *         attestation, this function checks that
      *           1) the hash corresponding to the _claimer and the _signature was committed
-     *           2) the _signature is signed correctly by the issuer
-     *           3) the _signature hasn't already been used to claim an invite before
-     *           4) the _signature issuer has not used up all of their invites
+     *           2) MIN_COMMITMENT_PERIOD has passed since the commitment was made.
+     *           3) the _signature is signed correctly by the issuer
+     *           4) the _signature hasn't already been used to claim an invite before
+     *           5) the _signature issuer has not used up all of their invites
      *         This function doesn't require that the _claimer is calling this function.
      *
      * @param _claimer         Address that will be granted the invite.
@@ -210,12 +233,22 @@ contract OptimistInviter is Semver, EIP712Upgradeable {
         ClaimableInvite calldata _claimableInvite,
         bytes memory _signature
     ) public {
+        uint256 commitmentTimestamp = commitmentTimestamps[
+            keccak256(abi.encode(_claimer, _signature))
+        ];
+
         // Make sure the claimer and signature have been committed.
         require(
-            commitments[keccak256(abi.encode(_claimer, _signature))],
+            commitmentTimestamp > 0,
             "OptimistInviter: claimer and signature have not been committed yet"
         );
 
+        // Check that MIN_COMMITMENT_PERIOD has passed since the commitment was made.
+        require(
+            commitmentTimestamp + MIN_COMMITMENT_PERIOD <= block.timestamp,
+            "OptimistInviter: minimum commitment period has not elapsed yet"
+        );
+
         // Generate a EIP712 typed data hash to compare against the signature.
         bytes32 digest = _hashTypedDataV4(
             keccak256(