From 1ca7eb1739526e666ec07ae5affb6940ae6381d6 Mon Sep 17 00:00:00 2001
From: Egor Homakov <homakov@gmail.com>
Date: Wed, 5 Aug 2015 22:41:47 +0300
Subject: [PATCH] Fix bug when v is < 1000000 and substr fails

For v less 1m e.g. 12345 previous code would try to get substr(-1,6). This happens once in 2130 attempts.
---
 index.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index fbd8605..b4718fc 100644
--- a/index.js
+++ b/index.js
@@ -43,9 +43,9 @@ hotp.gen = function(key, opt) {
 		(h[offset + 2] & 0xff) << 8  |
 		(h[offset + 3] & 0xff);
 
-	v = v + '';
+	v = (v % 1000000) + '';
 
-	return v.substr(v.length - p, p);
+	return Array(7-v.length).join('0') + v;
 };
 
 /**