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44 lines
1.4 KiB
44 lines
1.4 KiB
pragma solidity ^0.4.18;
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/*
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* @title MerkleProof
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* @dev Merkle proof verification
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* @note Based on https://github.com/ameensol/merkle-tree-solidity/blob/master/src/MerkleProof.sol
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*/
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library MerkleProof {
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/*
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* @dev Verifies a Merkle proof proving the existence of a leaf in a Merkle tree. Assumes that each pair of leaves
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* and each pair of pre-images is sorted.
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* @param _proof Merkle proof containing sibling hashes on the branch from the leaf to the root of the Merkle tree
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* @param _root Merkle root
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* @param _leaf Leaf of Merkle tree
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*/
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function verifyProof(bytes _proof, bytes32 _root, bytes32 _leaf) public pure returns (bool) {
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// Check if proof length is a multiple of 32
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if (_proof.length % 32 != 0) {
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return false;
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}
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bytes32 proofElement;
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bytes32 computedHash = _leaf;
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for (uint256 i = 32; i <= _proof.length; i += 32) {
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assembly {
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// Load the current element of the proof
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proofElement := mload(add(_proof, i))
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}
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if (computedHash < proofElement) {
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// Hash(current computed hash + current element of the proof)
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computedHash = keccak256(computedHash, proofElement);
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} else {
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// Hash(current element of the proof + current computed hash)
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computedHash = keccak256(proofElement, computedHash);
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}
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}
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// Check if the computed hash (root) is equal to the provided root
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return computedHash == _root;
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}
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}
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