75 lines
2.0 KiB
Solidity
75 lines
2.0 KiB
Solidity
pragma solidity >=0.5.0 <0.6.0;
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/**
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* @notice Uses ethereum signed messages
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*/
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contract MessageSigned {
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constructor() internal {}
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/**
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* @notice recovers address who signed the message
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* @param _signHash operation ethereum signed message hash
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* @param _messageSignature message `_signHash` signature
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*/
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function recoverAddress(
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bytes32 _signHash,
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bytes memory _messageSignature
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)
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internal
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pure
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returns(address)
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{
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uint8 v;
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bytes32 r;
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bytes32 s;
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(v,r,s) = signatureSplit(_messageSignature);
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return ecrecover(
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_signHash,
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v,
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r,
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s
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);
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}
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/**
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* @notice Hash a hash with `"\x19Ethereum Signed Message:\n32"`
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* @param _hash Sign to hash.
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* @return signHash Hash to be signed.
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*/
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function getSignHash(
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bytes32 _hash
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)
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internal
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pure
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returns (bytes32 signHash)
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{
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signHash = keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", _hash));
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}
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/**
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* @dev divides bytes signature into `uint8 v, bytes32 r, bytes32 s`
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*/
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function signatureSplit(bytes memory _signature)
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internal
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pure
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returns (uint8 v, bytes32 r, bytes32 s)
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{
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// The signature format is a compact form of:
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// {bytes32 r}{bytes32 s}{uint8 v}
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// Compact means, uint8 is not padded to 32 bytes.
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assembly {
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r := mload(add(_signature, 32))
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s := mload(add(_signature, 64))
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// Here we are loading the last 32 bytes, including 31 bytes
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// of 's'. There is no 'mload8' to do this.
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//
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// 'byte' is not working due to the Solidity parser, so lets
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// use the second best option, 'and'
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v := and(mload(add(_signature, 65)), 0xff)
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}
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require(v == 27 || v == 28, "Bad signature");
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}
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} |