Abstract signature to opaque bytearray

1 files changed, 77 insertions, 0 deletions

diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
new file mode 100644
index 000000000..919dbe312
--- /dev/null
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
@@ -0,0 +1,77 @@
+/*
+
+  Copyright 2017 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 ^0.4.19;
+
+import "./mixins/MSignatureValidator.sol";
+
+/// @dev Provides MSignatureValidator
+contract MixinSignatureValidator is
+    MSignatureValidator
+{
+    enum SignatureType {
+        Invalid,
+        Ecrecover
+    }
+  
+    function isValidSignature(
+        bytes32 hash,
+        address signer,
+        bytes signature)
+        public view
+        returns (bool isValid)
+    {
+        require(signature.length >= 1);
+        
+        // Select signature type
+        SignatureType signatureType = SignatureType(uint8(signature[0]));
+        if (signatureType != SignatureType.Ecrecover) {
+            valid = false;
+            return;
+        }
+        
+        // Verify using ecrecover
+        require(signature.length == 66);
+        uint8 v = uint8(signature[1]);
+        bytes32 r = get32(signature, 2);
+        bytes32 s = get32(signature, 34);
+        address recovered = ecrecover(
+            keccak256("\x19Ethereum Signed Message:\n32", hash),
+            v,
+            r,
+            s
+        );
+        isValid = signer == recovered;
+    }
+    
+    function get32(bytes b, uint256 index)
+        private pure
+        returns (bytes32 result)
+    {
+        require(b.length >= index + 32);
+        
+        // Arrays are prefixed by a 256 bit length parameter
+        index += 32;
+        
+        // Read the bytes32 from array memory
+        assembly {
+            result := mload(add(b, index))
+        }
+    }
+
+}