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Smart contract for decoding Matic Network's check point signer addresses
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| // SPDX-License-Identifier: MIT | |
| pragma solidity ^0.8.0; | |
| contract DecodeCheckpointSignerList { | |
| // Slice specified number of bytes from arbitrary length byte array, starting from certain index | |
| function slice(bytes memory payload, uint256 start, uint256 length) internal pure returns (bytes memory) { | |
| require(length + 31 >= length, "slice_overflow"); | |
| require(start + length >= start, "slice_overflow"); | |
| require(payload.length >= start + length, "slice_outOfBounds"); | |
| bytes memory tempBytes; | |
| assembly { | |
| switch iszero(length) | |
| case 0 { | |
| tempBytes := mload(0x40) | |
| let lengthmod := and(length, 31) | |
| let mc := add(add(tempBytes, lengthmod), mul(0x20, iszero(lengthmod))) | |
| let end := add(mc, length) | |
| for { | |
| let cc := add(add(add(payload, lengthmod), mul(0x20, iszero(lengthmod))), start) | |
| } lt(mc, end) { | |
| mc := add(mc, 0x20) | |
| cc := add(cc, 0x20) | |
| } { | |
| mstore(mc, mload(cc)) | |
| } | |
| mstore(tempBytes, length) | |
| mstore(0x40, and(add(mc, 31), not(31))) | |
| } | |
| default { | |
| tempBytes := mload(0x40) | |
| mstore(tempBytes, 0) | |
| mstore(0x40, add(tempBytes, 0x20)) | |
| } | |
| } | |
| return tempBytes; | |
| } | |
| // Given input data for transaction invoking `submitHeaderBlock(bytes data, bytes sigs)` | |
| // attempts to extract out data & signature fields | |
| // | |
| // Note: Function signature is also included in `payload` i.e. first 4 bytes, which will be | |
| // stripped out 👇 | |
| function decodeIntoDataAndSignature(bytes calldata payload) internal pure returns (bytes memory, bytes memory) { | |
| return abi.decode(slice(payload, 4, payload.length - 4), (bytes, bytes)); | |
| } | |
| // Given 👆 function call for extracting `data` from transaction input data | |
| // has succeeded, votehash can be computed, which was signed by these check point signers | |
| function computeVoteHash(bytes memory payload) internal pure returns (bytes32) { | |
| return keccak256(abi.encodePacked(hex"01", payload)); | |
| } | |
| // Attempt to recover signer address, given original message & signed message | |
| function ecrecovery(bytes32 voteHash, bytes memory sig) internal pure returns (bytes memory) { | |
| bytes32 r; | |
| bytes32 s; | |
| uint8 v; | |
| assembly { | |
| r := mload(add(sig, 32)) | |
| s := mload(add(sig, 64)) | |
| v := and(mload(add(sig, 65)), 255) | |
| } | |
| if (v < 27) v += 27; | |
| return addresstoBytes(ecrecover(voteHash, v, r, s)); | |
| } | |
| // Converts Ethereum address to bytes data type | |
| function addresstoBytes(address a) internal pure returns (bytes memory) { | |
| return abi.encodePacked(a); | |
| } | |
| // Passing transaction input data of `submitHeaderBlock(bytes data, bytes sigs)` function | |
| // call, it attempts to figure out what are those signers who signer this checkpoint | |
| // | |
| // Note: Sending checkpoint from Matic Network ( L2 ) to Ethereum Network ( L1 ) | |
| // is nothing but calling `submitHeaderBlock(bytes data, bytes sigs)`, defined | |
| // in RootChain contract, deployed on Ethereum Network, with proper arguments, by some validator. | |
| // | |
| // RootChain : | |
| // 0x2890bA17EfE978480615e330ecB65333b880928e [ Goerli ] | |
| // 0x86E4Dc95c7FBdBf52e33D563BbDB00823894C287 [ Ethereum Mainnet ] | |
| function decode(bytes calldata payload) external pure returns (bytes[] memory) { | |
| (bytes memory data, bytes memory sigs) = decodeIntoDataAndSignature(payload); | |
| bytes32 voteHash = computeVoteHash(data); | |
| bytes[] memory signers = new bytes[](sigs.length / 65); | |
| uint256 count = 0; | |
| for(uint256 i = 0; i < sigs.length; i += 65) { | |
| signers[count++] = ecrecovery(voteHash, slice(sigs, i, 65)); | |
| } | |
| return signers; | |
| } | |
| } |
DecodeCheckpointSignerList is deployed on
New revision to return checkpoint signer addresses in bytes[] form instead of address[].
👆 change is being made to address issue faced in Matic Network's The Graph deployment, where it requires addresses in Array<Bytes> form & conversion from Array<Address> to Array<Bytes> fails in runtime.
An issue was created in graph-ts repo, reporting this.
But this change probably solves aforementioned problem 😉.
Updated contract's deployment details:
Please use 👆 contracts if you need to get signer addresses back in bytes[] form
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Given check point submission transaction hash, input data for invocation of
RootChain.submitHeaderBlock(bytes data, bytes sigs), can be obtained very easily using web3js like 👇Now using 👆 contract's
decodemethod, all check point signer addresses can be determined very easily.decodeaccepts single parameter which isinputfield of transaction object 👆.Deployment details to be put 👇, in some time.