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Add witness verification on Bridge contract (#352)
* Add witness verification on Bridge * Use segwit txn as test data in Bridge contract test * Change deposit parameters to a struct in Bridge * Change L1BlockHashList address in Bridge * Remove block header from Bridge contract * Fix witness utils bugs * Witness inclusion in Bridge * Further tests for Bridge * Rename signature count in Bridge
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crates/evm/src/evm/system_contracts/lib/WitnessUtils.sol
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| // SPDX-License-Identifier: LGPL-3.0-or-later | ||
| pragma solidity ^0.8.4; | ||
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| /** @title WitnessUtils */ | ||
| /** @author Citrea, modified from Bitcoin-SPV */ | ||
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| import {BytesLib} from "bitcoin-spv/solidity/contracts/BytesLib.sol"; | ||
| import {SafeMath} from "bitcoin-spv/solidity/contracts/SafeMath.sol"; | ||
| import "bitcoin-spv/solidity/contracts/BTCUtils.sol"; | ||
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| library WitnessUtils { | ||
| using BytesLib for bytes; | ||
| using BTCUtils for bytes; | ||
| using SafeMath for uint256; | ||
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| function calculateWtxId( | ||
| bytes4 version, | ||
| bytes2 flag, | ||
| bytes calldata vin, | ||
| bytes calldata vout, | ||
| bytes calldata witness, | ||
| bytes4 locktime | ||
| ) internal view returns (bytes32) { | ||
| return abi.encodePacked(version, flag, vin, vout, witness, locktime).hash256View(); | ||
| } | ||
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| /// @notice Checks that the witness passed up is properly formatted | ||
| /// @param _witness Raw bytes length-prefixed witness vector | ||
| /// @param _nWits The number of witnesses expected, sourced from number of inputs | ||
| /// @return True if it represents a validly formatted witness | ||
| function validateWitness(bytes memory _witness, uint256 _nWits) internal pure returns (bool) { | ||
| // Not valid if it says there are no witnesses | ||
| if (_nWits == 0) { | ||
| return false; | ||
| } | ||
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| uint256 _offset = 0; | ||
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| for (uint256 i = 0; i < _nWits; i++) { | ||
| // If we're at the end, but still expect more | ||
| if (_offset >= _witness.length) { | ||
| return false; | ||
| } | ||
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| // Grab the next input and determine its length. | ||
| uint256 _nextLen = determineWitnessLengthAt(_witness, _offset); | ||
| if (_nextLen == BTCUtils.ERR_BAD_ARG) { | ||
| return false; | ||
| } | ||
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| // Increase the offset by that much | ||
| _offset += _nextLen; | ||
| } | ||
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| // Returns false if we're not exactly at the end | ||
| return _offset == _witness.length; | ||
| } | ||
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| /// @notice Determines the length of a witness, | ||
| /// starting at the specified position | ||
| /// @param _witness The byte array containing the witness vector | ||
| /// @param _at The position of the witness in the array | ||
| /// @return The length of the witness in bytes | ||
| function determineWitnessLengthAt(bytes memory _witness, uint256 _at) internal pure returns (uint256) { | ||
| uint256 _varIntDataLen; | ||
| uint256 _nWits; | ||
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| (_varIntDataLen, _nWits) = BTCUtils.parseVarIntAt(_witness, _at); | ||
| if (_varIntDataLen == BTCUtils.ERR_BAD_ARG) { | ||
| return BTCUtils.ERR_BAD_ARG; | ||
| } | ||
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| uint256 _itemLen; | ||
| uint256 _offset = 1 + _varIntDataLen; | ||
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| for (uint256 i = 0; i < _nWits; i++) { | ||
| (_varIntDataLen, _itemLen) = BTCUtils.parseVarIntAt(_witness, _offset); | ||
| if (_itemLen == BTCUtils.ERR_BAD_ARG) { | ||
| return BTCUtils.ERR_BAD_ARG; | ||
| } | ||
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| _offset += 1 + _varIntDataLen + _itemLen; | ||
| } | ||
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| return _offset; | ||
| } | ||
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| /// @notice Extracts the witness at a given index in the witnesses vector | ||
| /// @dev Iterates over the witness. If you need to extract multiple, write a custom function | ||
| /// @param _witness The witness vector to extract from | ||
| /// @param _index The 0-indexed location of the witness to extract | ||
| /// @return The specified witness | ||
| function extractWitnessAtIndex(bytes memory _witness, uint256 _index) internal pure returns (bytes memory) { | ||
| uint256 _len = 0; | ||
| uint256 _offset = 0; | ||
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| for (uint256 _i = 0; _i < _index; _i ++) { | ||
| _len = determineWitnessLengthAt(_witness, _offset); | ||
| require(_len != BTCUtils.ERR_BAD_ARG, "Bad VarInt in witness"); | ||
| _offset += _len; | ||
| } | ||
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| _len = determineWitnessLengthAt(_witness, _offset); | ||
| require(_len != BTCUtils.ERR_BAD_ARG, "Bad VarInt in witness"); | ||
| return _witness.slice(_offset, _len); | ||
| } | ||
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| /// @notice Extracts the item at a given index in the witness | ||
| /// @dev Iterates over the items. If you need to extract multiple, write a custom function | ||
| /// @param _witness The witness to extract from | ||
| /// @param _index The 0-indexed location of the item to extract | ||
| /// @return The specified item | ||
| function extractItemFromWitness(bytes memory _witness, uint256 _index) internal pure returns (bytes memory) { | ||
| uint256 _varIntDataLen; | ||
| uint256 _nItems; | ||
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| (_varIntDataLen, _nItems) = BTCUtils.parseVarInt(_witness); | ||
| require(_varIntDataLen != BTCUtils.ERR_BAD_ARG, "Read overrun during VarInt parsing"); | ||
| require(_index < _nItems, "Vin read overrun"); | ||
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| uint256 _itemLen = 0; | ||
| uint256 _offset = 1 + _varIntDataLen; | ||
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| for (uint256 i = 0; i < _index; i++) { | ||
| (_varIntDataLen, _itemLen) = BTCUtils.parseVarIntAt(_witness, _offset); | ||
| require(_itemLen != BTCUtils.ERR_BAD_ARG, "Bad VarInt in item"); | ||
| _offset += 1 + _varIntDataLen + _itemLen; | ||
| } | ||
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| (_varIntDataLen, _itemLen) = BTCUtils.parseVarIntAt(_witness, _offset); | ||
| require(_itemLen != BTCUtils.ERR_BAD_ARG, "Bad VarInt in item"); | ||
| return _witness.slice(_offset, _itemLen + _varIntDataLen + 1); | ||
| } | ||
| } |
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