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/*
Copyright 2018 ZeroEx Intl.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
pragma solidity ^0.4.24;
contract LibEIP712 {
// EIP191 header for EIP712 prefix
string constant internal EIP191_HEADER = "\x19\x01";
// EIP712 Domain Name value
string constant internal EIP712_DOMAIN_NAME = "0x Protocol";
// EIP712 Domain Version value
string constant internal EIP712_DOMAIN_VERSION = "2";
// Hash of the EIP712 Domain Separator Schema
bytes32 constant internal EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH = keccak256(abi.encodePacked(
"EIP712Domain(",
"string name,",
"string version,",
"address verifyingContract",
")"
));
// Hash of the EIP712 Domain Separator data
// solhint-disable-next-line var-name-mixedcase
bytes32 public EIP712_DOMAIN_HASH;
constructor ()
public
{
EIP712_DOMAIN_HASH = keccak256(abi.encodePacked(
EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH,
keccak256(bytes(EIP712_DOMAIN_NAME)),
keccak256(bytes(EIP712_DOMAIN_VERSION)),
bytes32(address(this))
));
}
/// @dev Calculates EIP712 encoding for a hash struct in this EIP712 Domain.
/// @param hashStruct The EIP712 hash struct.
/// @return EIP712 hash applied to this EIP712 Domain.
function hashEIP712Message(bytes32 hashStruct)
internal
view
returns (bytes32 result)
{
bytes32 eip712DomainHash = EIP712_DOMAIN_HASH;
// Assembly for more efficient computing:
// keccak256(abi.encodePacked(
// EIP191_HEADER,
// EIP712_DOMAIN_HASH,
// hashStruct
// ));
assembly {
// Load free memory pointer
let memPtr := mload(64)
mstore(memPtr, 0x1901000000000000000000000000000000000000000000000000000000000000) // EIP191 header
mstore(add(memPtr, 2), eip712DomainHash) // EIP712 domain hash
mstore(add(memPtr, 34), hashStruct) // Hash of struct
// Compute hash
result := keccak256(memPtr, 66)
}
return result;
}
}
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