From 62861d1e1315a14e955b30a45db05e7907b0d22d Mon Sep 17 00:00:00 2001
From: Fabio Berger <me@fabioberger.com>
Date: Thu, 9 Nov 2017 17:18:03 -0500
Subject: Move isValidSignature implementation into signatureUtils

---
 src/utils/signature_utils.ts | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'src/utils/signature_utils.ts')

diff --git a/src/utils/signature_utils.ts b/src/utils/signature_utils.ts
index b312b5554..d066f8bf0 100644
--- a/src/utils/signature_utils.ts
+++ b/src/utils/signature_utils.ts
@@ -2,6 +2,21 @@ import * as ethUtil from 'ethereumjs-util';
 import {ECSignature} from '../types';
 
 export const signatureUtils = {
+    isValidSignature(data: string, signature: ECSignature, signerAddress: string): boolean {
+        const dataBuff = ethUtil.toBuffer(data);
+        const msgHashBuff = ethUtil.hashPersonalMessage(dataBuff);
+        try {
+            const pubKey = ethUtil.ecrecover(
+                msgHashBuff,
+                signature.v,
+                ethUtil.toBuffer(signature.r),
+                ethUtil.toBuffer(signature.s));
+            const retrievedAddress = ethUtil.bufferToHex(ethUtil.pubToAddress(pubKey));
+            return retrievedAddress === signerAddress;
+        } catch (err) {
+            return false;
+        }
+    },
     parseSignatureHexAsVRS(signatureHex: string): ECSignature {
         const signatureBuffer = ethUtil.toBuffer(signatureHex);
         let v = signatureBuffer[0];
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