+ function getNumberOfEntropyBits(entropy) {
+ var bitsStr = entropy.binaryStr.length.toString();
+ // If using cards, assume they are not reused, thus additional entropy
+ // decreases as more cards are used. This means entropy is measured
+ // using n!, not base^n.
+ // eg the second last card can be only one of two, not one of fifty two
+ // so the added entropy for that card is only one bit at most
+ if (entropy.base.asInt == 52) {
+ var totalCombos = factorial(52);
+ var remainingCards = 52 - entropy.base.parts.length;
+ var remainingCombos = factorial(remainingCards);
+ var currentCombos = totalCombos.divide(remainingCombos);
+ bitsStr = currentCombos.toString(2).length.toString();
+ }
+ return bitsStr
+ }
+
+ function getEntropyTypeStr(entropy) {
+ var typeStr = entropy.base.str;
+ // Add some detail if these are cards
+ if (entropy.base.asInt == 52) {
+ var cardDetail = []; // array of message strings
+ // Detect duplicates
+ var dupes = [];
+ var dupeTracker = {};
+ for (var i=0; i<entropy.base.parts.length; i++) {
+ var card = entropy.base.parts[i];
+ if (card in dupeTracker) {
+ dupes.push(card);
+ }
+ dupeTracker[card] = true;
+ }
+ if (dupes.length > 0) {
+ var dupeWord = "duplicates";
+ if (dupes.length == 1) {
+ dupeWord = "duplicate";
+ }
+ var msg = dupes.length + " " + dupeWord + ": " + dupes.slice(0,3).join(" ");
+ if (dupes.length > 3) {
+ msg += "...";
+ }
+ cardDetail.push(msg);
+ }
+ // Detect full deck
+ var uniqueCards = [];
+ for (var uniqueCard in dupeTracker) {
+ uniqueCards.push(uniqueCard);
+ }
+ if (uniqueCards.length == 52) {
+ cardDetail.unshift("full deck");
+ }
+ // Add card details to typeStr
+ if (cardDetail.length > 0) {
+ typeStr += " (" + cardDetail.join(", ") + ")";
+ }
+ }
+ return typeStr;
+ }
+
+ // Depends on BigInteger
+ function factorial(n) {
+ if (n == 0) {
+ return 1;
+ }
+ f = BigInteger.ONE;
+ for (var i=1; i<=n; i++) {
+ f = f.multiply(new BigInteger(i));
+ }
+ return f;
+ }
+