library ECDSA {
	/**
	 * @dev Returns the address that signed a hashed message (`hash`) with
	 * `signature`. This address can then be used for verification purposes.
	 *
	 * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
	 * this function rejects them by requiring the `s` value to be in the lower
	 * half order, and the `v` value to be either 27 or 28.
	 *
	 * NOTE: This call _does not revert_ if the signature is invalid, or
	 * if the signer is otherwise unable to be retrieved. In those scenarios,
	 * the zero address is returned.
	 *
	 * IMPORTANT: `hash` _must_ be the result of a hash operation for the
	 * verification to be secure: it is possible to craft signatures that
	 * recover to arbitrary addresses for non-hashed data. A safe way to ensure
	 * this is by receiving a hash of the original message (which may otherwise
	 * be too long), and then calling {toEthSignedMessageHash} on it.
	 */
	function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
		// Check the signature length
		if (signature.length != 65) {
			return (address(0));
		}

		// Divide the signature in r, s and v variables
		bytes32 r;
		bytes32 s;
		uint8 v;

		// ecrecover takes the signature parameters, and the only way to get them
		// currently is to use assembly.
		// solhint-disable-next-line no-inline-assembly
		assembly {
			r := mload(add(signature, 0x20))
			s := mload(add(signature, 0x40))
			v := byte(0, mload(add(signature, 0x60)))
		}

		// 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) {
			return address(0);
		}

		v = v + 27;
		if (v != 27 && v != 28) {
			return address(0);
		}

		// If the signature is valid (and not malleable), return the signer address
		return ecrecover(hash, v, r, s);
	}

	/**
	 * @dev Returns an Ethereum Signed Message, created from a `hash`. This
	 * replicates the behavior of the
	 * https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign[`eth_sign`]
	 * JSON-RPC method.
	 *
	 * See {recover}.
	 */
	function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
		// 32 is the length in bytes of hash,
		// enforced by the type signature above
		return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
	}
}
/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
		// Check the signature length
		if (signature.length != 65) {
			return (address(0));
		}

		// Divide the signature in r, s and v variables
		bytes32 r;
		bytes32 s;
		uint8 v;

		// ecrecover takes the signature parameters, and the only way to get them
		// currently is to use assembly.
		// solhint-disable-next-line no-inline-assembly
		assembly {
			r := mload(add(signature, 0x20))
			s := mload(add(signature, 0x40))
			v := byte(0, mload(add(signature, 0x60)))
		}

		// 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) {
			return address(0);
		}

		v = v + 27;
		if (v != 27 && v != 28) {
			return address(0);
		}

		// If the signature is valid (and not malleable), return the signer address
		return ecrecover(hash, v, r, s);
	}
/**
 	 * @dev Returns the address that signed a hashed message (`hash`) with
 	 * `signature`. This address can then be used for verification purposes.
 	 *
 	 * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
 	 * this function rejects them by requiring the `s` value to be in the lower
 	 * half order, and the `v` value to be either 27 or 28.
 	 *
 	 * NOTE: This call _does not revert_ if the signature is invalid, or
 	 * if the signer is otherwise unable to be retrieved. In those scenarios,
 	 * the zero address is returned.
 	 *
 	 * IMPORTANT: `hash` _must_ be the result of a hash operation for the
 	 * verification to be secure: it is possible to craft signatures that
 	 * recover to arbitrary addresses for non-hashed data. A safe way to ensure
 	 * this is by receiving a hash of the original message (which may otherwise
 	 * be too long), and then calling {toEthSignedMessageHash} on it.
 	 */