XKCD Generator

// EFF Diceware wordlist: 7,776 common English words
import { EFF_WORDLIST } from './diceware-wordlist.js';

function generateXKCDPassphrase(wordCount = 4, separator = ' ') {
  const words = [];
  const randomValues = new Uint32Array(wordCount);
  crypto.getRandomValues(randomValues);

  for (let i = 0; i < wordCount; i++) {
    // Map random 32-bit integer to wordlist index [0, 7776)
    const index = randomValues[i] % EFF_WORDLIST.length;
    words.push(EFF_WORDLIST[index]);
  }

  const entropy = wordCount * Math.log2(EFF_WORDLIST.length);
  const combinations = Math.pow(EFF_WORDLIST.length, wordCount);

  return {
    passphrase: words.join(separator),
    wordCount,
    entropyBits: entropy.toFixed(1),
    combinations: combinations.toExponential(2),
    crackTime: estimateCrackTime(combinations)
  };
}

function estimateCrackTime(combinations) {
  const hashesPerSecond = 1e12; // GPU cluster
  const seconds = combinations / 2 / hashesPerSecond;
  if (seconds < 1) return 'Instant';
  if (seconds < 31536000) return (seconds / 86400).toFixed(0) + ' days';
  return (seconds / 31536000).toExponential(1) + ' years';
}

// Usage
const result = generateXKCDPassphrase(4);
console.log(result.passphrase); // e.g., "correct horse battery staple"
console.log(result.entropyBits); // "51.7"
console.log(result.crackTime); // "58.6 years"

// For high security:
const strong = generateXKCDPassphrase(6);
console.log(strong.entropyBits); // "77.5"

function generateXKCDWithConfig(config = {}) {
  const {
    words = 4,
    separator = ' ',
    capitalize = false,
    appendNumber = false
  } = config;

  // Generate random words
  const randomValues = new Uint32Array(words);
  crypto.getRandomValues(randomValues);

  let wordArray = Array.from(randomValues)
    .map(r => EFF_WORDLIST[r % EFF_WORDLIST.length]);

  // Optional: capitalize first letter of each word
  if (capitalize) {
    wordArray = wordArray.map(w =>
      w.charAt(0).toUpperCase() + w.slice(1)
    );
  }

  // Optional: append a random number
  let passphrase = wordArray.join(separator);
  if (appendNumber) {
    const numArray = new Uint32Array(1);
    crypto.getRandomValues(numArray);
    passphrase += separator + (numArray[0] % 100);
  }

  // Calculate entropy
  let entropy = words * Math.log2(EFF_WORDLIST.length);
  if (appendNumber) entropy += Math.log2(100);

  return {
    passphrase,
    entropyBits: entropy.toFixed(1)
  };
}

// Different configurations
console.log(generateXKCDWithConfig({ words: 4 }));
// "correct horse battery staple" — 51.7 bits

console.log(generateXKCDWithConfig({ words: 5, capitalize: true, appendNumber: true }));
// "Correct Horse Battery Staple 42" — 71.3 bits