}
// 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++) {
strength = strength + " - " + z.feedback.warning;
};
}
- var bitsStr = entropy.binaryStr.length;
+ var bitsStr = getNumberOfEntropyBits(entropy);
var wordCount = Math.floor(entropy.binaryStr.length / 32) * 3;
DOM.entropyFiltered.html(entropy.cleanHtml);
DOM.entropyType.text(entropy.base.str);
DOM.entropyBitsPerEvent.text(Math.log2(entropy.base.asInt).toFixed(2));
}
+ 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
+ }
+
+ // 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;
+ }
+
var networks = [
{
name: "Bitcoin",