Merkle树的Solidity合约

contracts/MerkleProof.sol

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+pragma solidity ^0.5.0;
+
+/**
+ * @title MerkleProof
+ * @dev Merkle proof verification based on https://github.com/ameensol/merkle-tree-solidity/blob/master/src/MerkleProof.sol
+ * Source: https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/MerkleProof.sol
+ */
+library MerkleProof {
+    /**
+     * @dev Verifies a Merkle proof proving the existence of a leaf in a Merkle tree. Assumes that each pair of leaves
+     * and each pair of pre-images are sorted.
+     * @param _proof Merkle proof containing sibling hashes on the branch from the leaf to the root of the Merkle tree
+     * @param _root Merkle root
+     * @param _leaf Leaf of Merkle tree
+     */
+    function verifyProof(
+        bytes32[] memory _proof,
+        bytes32 _root,
+        bytes32 _leaf
+    )
+        internal
+        pure
+        returns (bool)
+    {
+        bytes32 computedHash = _leaf;
+
+        for (uint256 i = 0; i < _proof.length; i++) {
+            bytes32 proofElement = _proof[i];
+
+            if (computedHash < proofElement) {
+                // Hash(current computed hash + current element of the proof)
+                computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
+            } else {
+                // Hash(current element of the proof + current computed hash)
+                computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
+            }
+        }
+
+        // Check if the computed hash (root) is equal to the provided root
+        return computedHash == _root;
+    }
+}