From d6fd8ebf8667cad13392aff185fa5da7a7e82cbe Mon Sep 17 00:00:00 2001
From: Ian Coleman <coleman.ian@gmail.com>
Date: Mon, 14 Nov 2016 13:21:04 +1100
Subject: [PATCH] Entropy is truncated from the left

This provides greater compatibility with bip32jp.github.io
---
 src/js/index.js | 3 ++-
 tests.js        | 8 +++-----
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/js/index.js b/src/js/index.js
index d356eb8..b03f2c8 100644
--- a/src/js/index.js
+++ b/src/js/index.js
@@ -764,7 +764,8 @@
         }
         // Discard trailing entropy
         var bitsToUse = Math.floor(bits.length / 32) * 32;
-        var binaryStr = bits.substring(0, bitsToUse);
+        var start = bits.length - bitsToUse;
+        var binaryStr = bits.substring(start);
         // Convert entropy string to numeric array
         var entropyArr = [];
         for (var i=0; i<binaryStr.length / 8; i++) {
diff --git a/tests.js b/tests.js
index 33477ac..9abe573 100644
--- a/tests.js
+++ b/tests.js
@@ -2696,15 +2696,15 @@ page.open(url, function(status) {
 });
 },
 
-// Entropy is truncated from the right
+// Entropy is truncated from the left
 function() {
 page.open(url, function(status) {
-    var expected = "abandon abandon ability";
+    var expected = "avocado zoo zone";
     // use entropy
     page.evaluate(function() {
         $(".use-entropy").prop("checked", true).trigger("change");
         var entropy  = "00000000 00000000 00000000 00000000";
-            entropy += "11111111 11111111 11111111 1111"; // Missing last byte, only first 8 bytes are used
+            entropy += "11111111 11111111 11111111 1111"; // Missing last byte
         $(".entropy").val(entropy).trigger("input");
     });
     // check the entropy is truncated from the right
@@ -2755,8 +2755,6 @@ page.open(url, function(status) {
 // https://bip32jp.github.io/english/index.html
 // NOTES:
 // Is incompatible with:
-//     base 6 with leading zeros
-//     base 6 wth 12 words / 53 chars
 //     base 20
 function() {
 page.open(url, function(status) {
-- 
2.41.0