From 43061c691b77bac625264b7b353583b405fa992b Mon Sep 17 00:00:00 2001
From: Richard Moore <github@ricmoo.com>
Date: Fri, 29 Dec 2017 20:44:32 -0500
Subject: [PATCH] Verify message supports normalized and non-normalized
 recovery parameter.

---
 wallet/package.json | 2 +-
 wallet/wallet.js    | 7 +++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/wallet/package.json b/wallet/package.json
index 8835914f..79dcd983 100644
--- a/wallet/package.json
+++ b/wallet/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ethers-wallet",
-  "version": "2.1.6",
+  "version": "2.1.7",
   "description": "Wallet and signing library for Ethereum.",
   "bugs": {
     "url": "http://github.com/ethers-io/ethers.js/issues",
diff --git a/wallet/wallet.js b/wallet/wallet.js
index b3555b06..0b105ac5 100644
--- a/wallet/wallet.js
+++ b/wallet/wallet.js
@@ -306,13 +306,16 @@ utils.defineProperty(Wallet, 'verifyMessage', function(message, signature) {
     signature = utils.hexlify(signature);
     if (signature.length != 132) { throw new Error('invalid signature'); }
     var digest = getHash(message);
-    var recoveryParam = parseInt(signature.substring(130), 16) - 27;
+
+    var recoveryParam = parseInt(signature.substring(130), 16);
+    if (recoveryParam >= 27) { recoveryParam -= 27; }
     if (recoveryParam < 0) { throw new Error('invalid signature'); }
+
     return SigningKey.recover(
         digest,
         signature.substring(0, 66),
         '0x' + signature.substring(66, 130),
-        parseInt(signature.substring(130), 16) - 27
+        recoveryParam
     );
 });