ECRecovery的Solidity合约

contracts/ECRecovery.sol

@@ -0,0 +1,68 @@
+pragma solidity ^0.5.0;
+
+/**
+ * @title Elliptic curve signature operations
+ * @dev Based on https://gist.github.com/axic/5b33912c6f61ae6fd96d6c4a47afde6d
+ * TODO Remove this library once solidity supports passing a signature to ecrecover.
+ * See https://github.com/ethereum/solidity/issues/864
+ * Source: https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/ECRecovery.sol
+ */
+library ECRecovery {
+    /**
+     * @dev Recover signer address from a message by using their signature
+     * @param _hash bytes32 message, the hash is the signed message. What is recovered is the signer address.
+     * @param _signature bytes signature, the signature is generated using web3.eth.sign()
+     */
+    function recover(bytes32 _hash, bytes memory _signature)
+        internal
+        pure
+        returns (address)
+    {
+        bytes32 r;
+        bytes32 s;
+        uint8 v;
+
+        // Check the signature length
+        if (_signature.length != 65) {
+            return (address(0));
+        }
+
+        // Divide the signature in r, s and v variables
+        // ecrecover takes the signature parameters, and the only way to get them
+        // currently is to use assembly.
+        // solium-disable-next-line security/no-inline-assembly
+        assembly {
+            r := mload(add(_signature, 32))
+            s := mload(add(_signature, 64))
+            v := byte(0, mload(add(_signature, 96)))
+        }
+
+        // Version of signature should be 27 or 28, but 0 and 1 are also possible versions
+        if (v < 27) {
+            v += 27;
+        }
+
+        // If the version is correct return the signer address
+        if (v != 27 && v != 28) {
+            return (address(0));
+        } else {
+            // solium-disable-next-line arg-overflow
+            return ecrecover(_hash, v, r, s);
+        }
+    }
+
+    /**
+     * @dev prefix a bytes32 value with "\x19Ethereum Signed Message:" and hash the result
+     */
+    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)
+        );
+    }
+}