44 lines
1.6 KiB
Solidity
44 lines
1.6 KiB
Solidity
// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.0;
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/**
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* @dev These functions deal with verification of Merkle Trees proofs.
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*
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* The proofs can be generated using the JavaScript library
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* https://github.com/miguelmota/merkletreejs[merkletreejs].
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* Note: the hashing algorithm should be keccak256 and pair sorting should be enabled.
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*
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* See `test/utils/cryptography/MerkleProof.test.js` for some examples.
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*/
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library MerkleProof {
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/**
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* @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
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* defined by `root`. For this, a `proof` must be provided, containing
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* sibling hashes on the branch from the leaf to the root of the tree. Each
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* pair of leaves and each pair of pre-images are assumed to be sorted.
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*/
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function verify(
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bytes32[] memory proof,
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bytes32 root,
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bytes32 leaf
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) internal pure returns (bool) {
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bytes32 computedHash = leaf;
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for (uint256 i = 0; i < proof.length; i++) {
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bytes32 proofElement = proof[i];
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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(abi.encodePacked(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(abi.encodePacked(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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