add BTG (Bitcoin Gold/bgold)

[perso/Immae/Projets/Cryptomonnaies/BIP39.git] / src / js / entropy.js

diff --git a/src/js/entropy.js b/src/js/entropy.js
index b7274bbea7ccb5781aa084b45d0219d5e99e4e0e..a709c782a171855e3f3ba875af1c39ef73890ab4 100644 (file)
--- a/src/js/entropy.js
+++ b/src/js/entropy.js
@@ -263,7 +263,12 @@ window.Entropy = new (function() {
         }
         // Work out the total number of bits for this many decks
         // See http://crypto.stackexchange.com/q/41886
-        var gainedBits = Math.log2(factorial(52 * numberOfDecks));
+        var gainedBits = 0;
+        // Equivalent of Math.log2(factorial(52*numberOfDecks))
+        // which becomes infinity for numberOfDecks > 4
+        for (var i=1; i<=52*numberOfDecks; i++) {
+            gainedBits = gainedBits + Math.log2(i);
+        }
         var lostBits = 52 * Math.log2(factorial(numberOfDecks));
         var maxBits = gainedBits - lostBits;
         // Convert the drawn cards to a binary representation.
@@ -288,15 +293,12 @@ window.Entropy = new (function() {
         // Create a normalized string of the selected cards
         var normalizedCards = cards.join("").toUpperCase();
         // Convert to binary using the SHA256 hash of the normalized cards.
-        // If the number of bits is more than 256, multiple rounds of hashing
+        // If the number of bits is more than 256, multiple hashes
         // are used until the required number of bits is reached.
         var entropyBin = "";
         var iterations = 0;
         while (entropyBin.length < numberOfBits) {
-            var hashedCards = sjcl.hash.sha256.hash(normalizedCards);
-            for (var j=0; j<iterations; j++) {
-                hashedCards = sjcl.hash.sha256.hash(hashedCards);
-            }
+            var hashedCards = sjcl.hash.sha256.hash(normalizedCards + ":" + iterations);
             var hashHex = sjcl.codec.hex.fromBits(hashedCards);
             for (var i=0; i<hashHex.length; i++) {
                 var decimal = parseInt(hashHex[i], 16);