Contract Name:
SignatureChecker
Contract Source Code:
/**
* Copyright 2023 Circle Internet Financial, LTD. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* 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 0.6.12;
import { ECRecover } from "./ECRecover.sol";
import { IERC1271 } from "../interface/IERC1271.sol";
/**
* @dev Signature verification helper that can be used instead of `ECRecover.recover` to seamlessly support both ECDSA
* signatures from externally owned accounts (EOAs) as well as ERC1271 signatures from smart contract wallets.
*
* Adapted from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/21bb89ef5bfc789b9333eb05e3ba2b7b284ac77c/contracts/utils/cryptography/SignatureChecker.sol
*/
library SignatureChecker {
/**
* @dev Checks if a signature is valid for a given signer and data hash. If the signer is a smart contract, the
* signature is validated against that smart contract using ERC1271, otherwise it's validated using `ECRecover.recover`.
* @param signer Address of the claimed signer
* @param digest Keccak-256 hash digest of the signed message
* @param signature Signature byte array associated with hash
*/
function isValidSignatureNow(
address signer,
bytes32 digest,
bytes memory signature
) external view returns (bool) {
if (!isContract(signer)) {
return ECRecover.recover(digest, signature) == signer;
}
return isValidERC1271SignatureNow(signer, digest, signature);
}
/**
* @dev Checks if a signature is valid for a given signer and data hash. The signature is validated
* against the signer smart contract using ERC1271.
* @param signer Address of the claimed signer
* @param digest Keccak-256 hash digest of the signed message
* @param signature Signature byte array associated with hash
*
* NOTE: Unlike ECDSA signatures, contract signatures are revocable, and the outcome of this function can thus
* change through time. It could return true at block N and false at block N+1 (or the opposite).
*/
function isValidERC1271SignatureNow(
address signer,
bytes32 digest,
bytes memory signature
) internal view returns (bool) {
(bool success, bytes memory result) = signer.staticcall(
abi.encodeWithSelector(
IERC1271.isValidSignature.selector,
digest,
signature
)
);
return (success &&
result.length >= 32 &&
abi.decode(result, (bytes32)) ==
bytes32(IERC1271.isValidSignature.selector));
}
/**
* @dev Checks if the input address is a smart contract.
*/
function isContract(address addr) internal view returns (bool) {
uint256 size;
assembly {
size := extcodesize(addr)
}
return size > 0;
}
}
/**
* Copyright 2023 Circle Internet Financial, LTD. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* 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 0.6.12;
/**
* @title ECRecover
* @notice A library that provides a safe ECDSA recovery function
*/
library ECRecover {
/**
* @notice Recover signer's address from a signed message
* @dev Adapted from: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/65e4ffde586ec89af3b7e9140bdc9235d1254853/contracts/cryptography/ECDSA.sol
* Modifications: Accept v, r, and s as separate arguments
* @param digest Keccak-256 hash digest of the signed message
* @param v v of the signature
* @param r r of the signature
* @param s s of the signature
* @return Signer address
*/
function recover(
bytes32 digest,
uint8 v,
bytes32 r,
bytes32 s
) internal pure returns (address) {
// EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
// unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
// the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
// signatures from current libraries generate a unique signature with an s-value in the lower half order.
//
// If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
// with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
// vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
// these malleable signatures as well.
if (
uint256(s) >
0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0
) {
revert("ECRecover: invalid signature 's' value");
}
if (v != 27 && v != 28) {
revert("ECRecover: invalid signature 'v' value");
}
// If the signature is valid (and not malleable), return the signer address
address signer = ecrecover(digest, v, r, s);
require(signer != address(0), "ECRecover: invalid signature");
return signer;
}
/**
* @notice Recover signer's address from a signed message
* @dev Adapted from: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/0053ee040a7ff1dbc39691c9e67a69f564930a88/contracts/utils/cryptography/ECDSA.sol
* @param digest Keccak-256 hash digest of the signed message
* @param signature Signature byte array associated with hash
* @return Signer address
*/
function recover(bytes32 digest, bytes memory signature)
internal
pure
returns (address)
{
require(signature.length == 65, "ECRecover: invalid signature length");
bytes32 r;
bytes32 s;
uint8 v;
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
/// @solidity memory-safe-assembly
assembly {
r := mload(add(signature, 0x20))
s := mload(add(signature, 0x40))
v := byte(0, mload(add(signature, 0x60)))
}
return recover(digest, v, r, s);
}
}
/**
* Copyright 2023 Circle Internet Financial, LTD. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* 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 0.6.12;
/**
* @dev Interface of the ERC1271 standard signature validation method for
* contracts as defined in https://eips.ethereum.org/EIPS/eip-1271[ERC-1271].
*/
interface IERC1271 {
/**
* @dev Should return whether the signature provided is valid for the provided data
* @param hash Hash of the data to be signed
* @param signature Signature byte array associated with the provided data hash
* @return magicValue bytes4 magic value 0x1626ba7e when function passes
*/
function isValidSignature(bytes32 hash, bytes memory signature)
external
view
returns (bytes4 magicValue);
}