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Entropy library has extra comments for clarity

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Ian Coleman
2016-11-17 14:31:57 +11:00
parent 6422c1cd57
commit 0fdcf2eb53
1 changed files with 5 additions and 3 deletions
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src/js/entropy.js
+5 -3
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@@ -7,6 +7,7 @@
* dice 6 [1-6] * dice 6 [1-6]
* decimal [0-9] * decimal [0-9]
* hexadecimal [0-9A-F] * hexadecimal [0-9A-F]
* card [A2-9TJQK][CDHS]
* *
* Automatically uses lowest entropy to avoid issues such as interpretting 0101 * Automatically uses lowest entropy to avoid issues such as interpretting 0101
* as hexadecimal which would be 16 bits when really it's only 4 bits of binary * as hexadecimal which would be 16 bits when really it's only 4 bits of binary
@@ -119,11 +120,11 @@ window.Entropy = new (function() {
} }
// Assume cards are NOT replaced. // Assume cards are NOT replaced.
// Additional entropy decreases as more cards are used. This means // Additional entropy decreases as more cards are used. This means
// entropy is measured using n!, not base^n. // total possible entropy is measured using n!, not base^n.
// eg the second last card can be only one of two, not one of fifty two // 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 // so the added entropy for that card is only one bit at most
if (base.asInt == 52) { if (base.asInt == 52) {
// Get the maximum value without replacement // Get the maximum value WITHOUT replacement
var totalDecks = Math.ceil(base.parts.length / 52); var totalDecks = Math.ceil(base.parts.length / 52);
var totalCards = totalDecks * 52; var totalCards = totalDecks * 52;
var totalCombos = factorial(52).pow(totalDecks); var totalCombos = factorial(52).pow(totalDecks);
@@ -140,7 +141,7 @@ window.Entropy = new (function() {
if (numberOfBits < 32) { if (numberOfBits < 32) {
maxWithoutReplace = BigInteger(Math.round(Math.pow(2, numberOfBits))); maxWithoutReplace = BigInteger(Math.round(Math.pow(2, numberOfBits)));
} }
// Get the maximum value with replacement // Get the maximum value WITH replacement
var maxWithReplace = BigInteger.pow(52, base.parts.length); var maxWithReplace = BigInteger.pow(52, base.parts.length);
// Calculate the new value by scaling the original value down // Calculate the new value by scaling the original value down
var withoutReplace = entropyInt.multiply(maxWithoutReplace).divide(maxWithReplace); var withoutReplace = entropyInt.multiply(maxWithoutReplace).divide(maxWithReplace);
@@ -166,6 +167,7 @@ window.Entropy = new (function() {
entropyHtml = entropyHtml.replace(/H/g, "<span class='card-suit heart'>\u2665</span>"); entropyHtml = entropyHtml.replace(/H/g, "<span class='card-suit heart'>\u2665</span>");
entropyHtml = entropyHtml.replace(/S/g, "<span class='card-suit spade'>\u2660</span>"); entropyHtml = entropyHtml.replace(/S/g, "<span class='card-suit spade'>\u2660</span>");
} }
// Return the result
var e = { var e = {
binaryStr: entropyBin, binaryStr: entropyBin,
cleanStr: entropyClean, cleanStr: entropyClean,