and removed the duplicate logic from the UI logic.
while (entropyBin.length < expectedBits) {
entropyBin = "0" + entropyBin;
}
+ // Assume cards are NOT replaced.
+ // 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 (base.asInt == 52) {
+ // Get the maximum value without replacement
+ var totalDecks = Math.ceil(base.parts.length / 52);
+ var totalCards = totalDecks * 52;
+ var totalCombos = factorial(52).pow(totalDecks);
+ var totalRemainingCards = totalCards - base.parts.length;
+ var remainingDecks = Math.floor(totalRemainingCards / 52);
+ var remainingCards = totalRemainingCards % 52;
+ var remainingCombos = factorial(52).pow(remainingDecks).multiply(factorial(remainingCards));
+ var currentCombos = totalCombos.divide(remainingCombos);
+ var numberOfBits = Math.log2(currentCombos);
+ var maxWithoutReplace = BigInteger.pow(2, numberOfBits);
+ // aggresive flooring of numberOfBits by BigInteger.pow means a
+ // more accurate result can be had for small numbers using the
+ // built-in Math.pow function.
+ if (numberOfBits < 32) {
+ maxWithoutReplace = BigInteger(Math.round(Math.pow(2, numberOfBits)));
+ }
+ // Get the maximum value with replacement
+ var maxWithReplace = BigInteger.pow(52, base.parts.length);
+ // Calculate the new value by scaling the original value down
+ var withoutReplace = entropyInt.multiply(maxWithoutReplace).divide(maxWithReplace);
+ // Left pad with zeros based on number of bits
+ var entropyBin = withoutReplace.toString(2);
+ var numberOfBitsInt = Math.floor(numberOfBits);
+ while (entropyBin.length < numberOfBitsInt) {
+ entropyBin = "0" + entropyBin;
+ }
+ }
// Supply a 'filtered' entropy string for display purposes
var entropyClean = base.parts.join("");
var entropyHtml = base.parts.join("");
return BigInteger.log(x) / BigInteger.log(2);
};
+ // 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;
+ }
+
})();
}
function showEntropyFeedback(entropy) {
+ var numberOfBits = entropy.binaryStr.length;
var strength = "extremely weak";
- if (entropy.binaryStr.length >= 64) {
+ if (numberOfBits >= 64) {
strength = "very weak";
}
- if (entropy.binaryStr.length >= 96) {
+ if (numberOfBits >= 96) {
strength = "weak";
}
- if (entropy.binaryStr.length >= 128) {
+ if (numberOfBits >= 128) {
strength = "strong";
}
- if (entropy.binaryStr.length >= 160) {
+ if (numberOfBits >= 160) {
strength = "very strong";
}
- if (entropy.binaryStr.length >= 192) {
+ if (numberOfBits >= 192) {
strength = "extremely strong";
}
// If time to crack is less than one day, and password is considered
console.log("Error detecting entropy strength with zxcvbn:");
console.log(e);
}
- var bitsStr = getNumberOfEntropyBits(entropy);
- var wordCount = Math.floor(entropy.binaryStr.length / 32) * 3;
var entropyTypeStr = getEntropyTypeStr(entropy);
+ var wordCount = Math.floor(numberOfBits / 32) * 3;
+ var bitsPerEvent = Math.log2(entropy.base.asInt).toFixed(2);
DOM.entropyFiltered.html(entropy.cleanHtml);
DOM.entropyType.text(entropyTypeStr);
DOM.entropyStrength.text(strength);
DOM.entropyEventCount.text(entropy.base.ints.length);
- DOM.entropyBits.text(bitsStr);
+ DOM.entropyBits.text(numberOfBits);
DOM.entropyWordCount.text(wordCount);
DOM.entropyBinary.text(entropy.binaryStr);
- 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 totalDecks = Math.ceil(entropy.base.parts.length / 52);
- var totalCards = totalDecks * 52;
- var totalCombos = factorial(52).pow(totalDecks);
- var totalRemainingCards = totalCards - entropy.base.parts.length;
- var remainingDecks = Math.floor(totalRemainingCards / 52);
- var remainingCards = totalRemainingCards % 52;
- var remainingCombos = factorial(52).pow(remainingDecks) * factorial(remainingCards);
- var currentCombos = totalCombos.divide(remainingCombos);
- bitsStr = currentCombos.toString(2).length.toString();
- }
- return bitsStr
+ DOM.entropyBitsPerEvent.text(bitsPerEvent);
}
function getEntropyTypeStr(entropy) {
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;
- }
-
var networks = [
{
name: "Bitcoin",
try {
var cards = [
[ "ac", "00000" ],
- [ "acac", "00000000000" ],
- [ "acac2c", "00000000000000001" ],
- [ "acks", "00000110011" ],
- [ "acacks", "00000000000110011" ],
+ [ "acqs", "00000110001" ],
+ [ "acks", "00000110010" ],
+ [ "2cac", "00000110011" ],
[ "2c", "00001" ],
[ "3d", "01111" ],
[ "4h", "11101" ],
[ "jd", "10111" ],
[ "qh", "100101" ],
[ "ks", "110011" ],
- [ "ks2c", "101001011101" ],
- [ "KS2C", "101001011101" ],
+ [ "ks2c", "101000101001" ],
+ [ "KS2C", "101000101001" ],
];
for (var i=0; i<cards.length; i++) {
var card = cards[i][0];
[ "222F", "16" ],
[ "FFFF", "16" ],
[ "0000101017", "33" ], // 10 events at 3.32 bits per event
- [ "ac2c3c4c5c6c7c8c9ctcjcqckcad2d3d4d5d6d7d8d9dtdjdqdkdah2h3h4h5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqsks", "226" ], // cards are not replaced, so a full deck is not 52^52 entropy which is 296 bits, it's 52!, which is 226 bits
+ [ "ac2c3c4c5c6c7c8c9ctcjcqckcad2d3d4d5d6d7d8d9dtdjdqdkdah2h3h4h5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqsks", "225" ], // cards are not replaced, so a full deck is not 52^52 entropy which is 296 bits, it's 52!, which is 225 bits
]
// use entropy
page.evaluate(function(e) {
entropy: "ac2c3c4c5c6c7c8c9ctcjcqckcad2d3d4d5d6d7d8d9dtdjdqdkdah2h3h4h5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqsks",
type: "card (full deck)",
events: 52,
- bits: 226,
- words: 27,
+ bits: 225,
+ words: 21,
strength: "extremely strong",
},
{
entropy: "ac2c3c4c5c6c7c8c9ctcjcqckcad2d3d4d5d6d7d8d9dtdjdqdkdah2h3h4h5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqsks3d",
type: "card (full deck, 1 duplicate: 3d)",
events: 53,
- bits: 232,
- words: 27,
+ bits: 231,
+ words: 21,
strength: "extremely strong",
},
{
entropy: "ac2c3c4c5c6c7c8c9ctcjcqckcad2d3d4d5d6d7d8d9dtdjdqdkdah2h3h4h5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqs3d4d",
type: "card (2 duplicates: 3d 4d, 1 missing: KS)",
events: 53,
- bits: 232,
- words: 27,
+ bits: 231,
+ words: 21,
strength: "extremely strong",
},
{
entropy: "ac2c3c4c5c6c7c8c9ctcjcqckcad2d3d4d5d6d7d8d9dtdjdqdkdah2h3h4h5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqs3d4d5d6d",
type: "card (4 duplicates: 3d 4d 5d..., 1 missing: KS)",
events: 53,
- bits: 243,
- words: 27,
+ bits: 242,
+ words: 21,
strength: "extremely strong",
},
// Next test was throwing uncaught error in zxcvbn
+ // Also tests 451 bits, ie Math.log2(52!)*2 = 225.58 * 2
{
entropy: "ac2c3c4c5c6c7c8c9ctcjcqckcad2d3d4d5d6d7d8d9dtdjdqdkdah2h3h4h5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqsksac2c3c4c5c6c7c8c9ctcjcqckcad2d3d4d5d6d7d8d9dtdjdqdkdah2h3h4h5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqsks",
type: "card (full deck, 52 duplicates: ac 2c 3c...)",
events: 104,
- bits: 452,
- words: 54,
+ bits: 451,
+ words: 42,
strength: "extremely strong",
},
// Case insensitivity to duplicate cards
entropy: "ac2c3c4c5c6c7c8c tcjcqckcad2d3d4d5d6d7d8d9dtdjdqdkdah2h3h4h5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqsks",
type: "card (1 missing: 9C)",
events: 51,
- bits: 226,
- words: 27,
+ bits: 225,
+ words: 21,
strength: "extremely strong",
},
{
entropy: "ac2c3c4c5c6c7c8c tcjcqckcad2d3d4d 6d7d8d9dtdjdqdkdah2h3h4h5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqsks",
type: "card (2 missing: 9C 5D)",
events: 50,
- bits: 225,
- words: 24,
+ bits: 224,
+ words: 21,
strength: "extremely strong",
},
{
entropy: "ac2c3c4c5c6c7c8c tcjcqckcad2d3d4d 6d7d8d9dtdjd kdah2h3h 5h6h7h8h9hthjhqhkhas2s3s4s5s6s7s8s9stsjsqsks",
type: "card (4 missing: 9C 5D QD...)",
events: 48,
- bits: 221,
- words: 24,
+ bits: 220,
+ words: 18,
strength: "extremely strong",
},
// More than six missing cards does not show message
entropy: "ac2c3c4c5c6c7c8c tcjcqckcad2d3d4d 6d 8d9d jd kdah2h3h 5h6h7h8h9hthjhqhkh 2s3s4s5s6s7s8s9stsjsqsks",
type: "card",
events: 45,
- bits: 214,
- words: 24,
+ bits: 213,
+ words: 18,
strength: "extremely strong",
},
];