feat: apply minor changes to SparseMerkleProof lib

Consensys · May 2, 2024 · b34c12c · b34c12c
1 parent ab293aa
commit b34c12c
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Showing 2 changed files with 34 additions and 40 deletions.
diff --git a/packages/l1-contracts/contracts/linea-verifier/lib/SparseMerkleProof.sol b/packages/l1-contracts/contracts/linea-verifier/lib/SparseMerkleProof.sol
@@ -25,6 +25,7 @@ library SparseMerkleProof {
     error WrongBytesLength(uint256 expectedLength, uint256 bytesLength);
 
     uint256 internal constant TREE_DEPTH = 40;
+    bytes32 internal constant ZERO_HASH = 0x0;
 
     /**
      * @notice Format input and verify sparse merkle proof
@@ -162,23 +163,24 @@ library SparseMerkleProof {
         bytes[] calldata _rawProof
     ) private pure returns (bytes32, bytes32, bytes32[] memory) {
         uint256 rawProofLength = _rawProof.length;
+        uint256 formattedProofLength = rawProofLength - 2;
 
-        bytes32[] memory proof = new bytes32[](rawProofLength - 2);
+        bytes32[] memory proof = new bytes32[](formattedProofLength);
         bytes32 nextFreeNode = bytes32(_rawProof[0][:32]);
         bytes32 leafHash = Mimc.hash(_rawProof[rawProofLength - 1]);
 
-        for (uint256 i = 1; i < rawProofLength - 2; ) {
-            proof[rawProofLength - 2 - i] = Mimc.hash(_rawProof[i]);
+        for (uint256 i = 1; i < formattedProofLength; ) {
+            proof[formattedProofLength - i] = Mimc.hash(_rawProof[i]);
             unchecked {
                 ++i;
             }
         }
 
-        // If the neighboring leaf is equal to zero bytes we don't hash it
-        if (_isZeroBytes(_rawProof[rawProofLength - 2])) {
-            proof[0] = bytes32(0);
+        // If the sibling leaf (_rawProof[formattedProofLength]) is equal to zero bytes we don't hash it
+        if (_isZeroBytes(_rawProof[formattedProofLength])) {
+            proof[0] = ZERO_HASH;
         } else {
-            proof[0] = Mimc.hash(_rawProof[rawProofLength - 2]);
+            proof[0] = Mimc.hash(_rawProof[formattedProofLength]);
         }
 
         return (nextFreeNode, leafHash, proof);
@@ -187,29 +189,28 @@ library SparseMerkleProof {
     /**
      * @notice Check if bytes contain only zero byte elements
      * @param _data Bytes to be checked
-     * @return {bool} true if bytes contain only zero byte elements, false otherwise
+     * @return isZeroBytes true if bytes contain only zero byte elements, false otherwise
      */
-    function _isZeroBytes(bytes calldata _data) private pure returns (bool) {
-        bool allZero = true;
+    function _isZeroBytes(
+        bytes calldata _data
+    ) private pure returns (bool isZeroBytes) {
+        isZeroBytes = true;
         assembly {
-            let dataLength := _data.length
             let dataStart := _data.offset
-            let dataEnd := add(dataStart, dataLength)
 
             for {
                 let currentPtr := dataStart
-            } lt(currentPtr, dataEnd) {
+            } lt(currentPtr, add(dataStart, _data.length)) {
                 currentPtr := add(currentPtr, 0x20)
             } {
                 let dataWord := calldataload(currentPtr)
 
                 if eq(iszero(dataWord), 0) {
-                    allZero := 0
+                    isZeroBytes := 0
                     break
                 }
             }
         }
-        return allZero;
     }
 
     /**
@@ -230,7 +231,7 @@ library SparseMerkleProof {
         bytes32 computedHash = _leafHash;
         uint256 currentIndex = _leafIndex;
 
-        for (uint256 height; height < TREE_DEPTH; ) {
+        for (uint256 height; height < TREE_DEPTH; ++height) {
             if ((currentIndex >> height) & 1 == 1)
                 computedHash = Mimc.hash(
                     abi.encodePacked(_proof[height], computedHash)
@@ -239,10 +240,6 @@ library SparseMerkleProof {
                 computedHash = Mimc.hash(
                     abi.encodePacked(computedHash, _proof[height])
                 );
-
-            unchecked {
-                ++height;
-            }
         }
 
         return

diff --git a/packages/linea-verifier/contracts/lib/SparseMerkleProof.sol b/packages/linea-verifier/contracts/lib/SparseMerkleProof.sol
@@ -25,6 +25,7 @@ library SparseMerkleProof {
     error WrongBytesLength(uint256 expectedLength, uint256 bytesLength);
 
     uint256 internal constant TREE_DEPTH = 40;
+    bytes32 internal constant ZERO_HASH = 0x0;
 
     /**
      * @notice Format input and verify sparse merkle proof
@@ -162,23 +163,24 @@ library SparseMerkleProof {
         bytes[] calldata _rawProof
     ) private pure returns (bytes32, bytes32, bytes32[] memory) {
         uint256 rawProofLength = _rawProof.length;
+        uint256 formattedProofLength = rawProofLength - 2;
 
-        bytes32[] memory proof = new bytes32[](rawProofLength - 2);
+        bytes32[] memory proof = new bytes32[](formattedProofLength);
         bytes32 nextFreeNode = bytes32(_rawProof[0][:32]);
         bytes32 leafHash = Mimc.hash(_rawProof[rawProofLength - 1]);
 
-        for (uint256 i = 1; i < rawProofLength - 2; ) {
-            proof[rawProofLength - 2 - i] = Mimc.hash(_rawProof[i]);
+        for (uint256 i = 1; i < formattedProofLength; ) {
+            proof[formattedProofLength - i] = Mimc.hash(_rawProof[i]);
             unchecked {
                 ++i;
             }
         }
 
-        // If the neighboring leaf is equal to zero bytes we don't hash it
-        if (_isZeroBytes(_rawProof[rawProofLength - 2])) {
-            proof[0] = bytes32(0);
+        // If the sibling leaf (_rawProof[formattedProofLength]) is equal to zero bytes we don't hash it
+        if (_isZeroBytes(_rawProof[formattedProofLength])) {
+            proof[0] = ZERO_HASH;
         } else {
-            proof[0] = Mimc.hash(_rawProof[rawProofLength - 2]);
+            proof[0] = Mimc.hash(_rawProof[formattedProofLength]);
         }
 
         return (nextFreeNode, leafHash, proof);
@@ -187,29 +189,28 @@ library SparseMerkleProof {
     /**
      * @notice Check if bytes contain only zero byte elements
      * @param _data Bytes to be checked
-     * @return {bool} true if bytes contain only zero byte elements, false otherwise
+     * @return isZeroBytes true if bytes contain only zero byte elements, false otherwise
      */
-    function _isZeroBytes(bytes calldata _data) private pure returns (bool) {
-        bool allZero = true;
+    function _isZeroBytes(
+        bytes calldata _data
+    ) private pure returns (bool isZeroBytes) {
+        isZeroBytes = true;
         assembly {
-            let dataLength := _data.length
             let dataStart := _data.offset
-            let dataEnd := add(dataStart, dataLength)
 
             for {
                 let currentPtr := dataStart
-            } lt(currentPtr, dataEnd) {
+            } lt(currentPtr, add(dataStart, _data.length)) {
                 currentPtr := add(currentPtr, 0x20)
             } {
                 let dataWord := calldataload(currentPtr)
 
                 if eq(iszero(dataWord), 0) {
-                    allZero := 0
+                    isZeroBytes := 0
                     break
                 }
             }
         }
-        return allZero;
     }
 
     /**
@@ -230,7 +231,7 @@ library SparseMerkleProof {
         bytes32 computedHash = _leafHash;
         uint256 currentIndex = _leafIndex;
 
-        for (uint256 height; height < TREE_DEPTH; ) {
+        for (uint256 height; height < TREE_DEPTH; ++height) {
             if ((currentIndex >> height) & 1 == 1)
                 computedHash = Mimc.hash(
                     abi.encodePacked(_proof[height], computedHash)
@@ -239,10 +240,6 @@ library SparseMerkleProof {
                 computedHash = Mimc.hash(
                     abi.encodePacked(computedHash, _proof[height])
                 );
-
-            unchecked {
-                ++height;
-            }
         }
 
         return