seedprotect.js

seedprotect.js

const crypto = require('crypto');

function lpad(str, padString, length) {
  while (str.length < length) str = padString + str;
  return str;
}

// converts string '1100' to integer 12
function binaryToByte(bin) {
  return parseInt(bin, 2);
}

// returns string, like: '10011'
function bytesToBinary(bytes) {
  return bytes.map(x => lpad(x.toString(2), '0', 8)).join('');
}

function getChunks(password) {
  // create pseudo-random 256 bits based on password
  const hash = crypto
    .createHash('sha256')
    .update(password)
    .digest();

  // get actual bits as string, like: '10011000111...'
  const bits = bytesToBinary([].slice.call(hash));

  // separate in chunks of 5 bits (= 32 combinations)
  return bits.match(/.{1,5}/g);
}

function shuffle(mnemonic, password) {
  if (password.trim() == '') {
    return mnemonic;
  }

  const chunks = getChunks(password);

  const words = mnemonic.split(' ');
  const shuffled = [];

  // Fisher–Yates shuffle:
  // The algorithm effectively puts all the elements into a hat; it continually determines the next element by randomly drawing an element from the hat until no elements remain.
  while (words.length > 0) {
    const chunk = chunks.splice(0, 1);
    const index = binaryToByte(chunk) % words.length;
    shuffled.push(words.splice(index, 1));
  }

  return shuffled.join(' ');
}

const mnemonic =
  'word1 word2 word3 word4 word5 word6 word7 word8 word9 word10 word11 word12 word13 word14 word15 word16 word17 word18 word19 word20 word21 word22 word23 word24';

const password = 'PASSWORD';

const shuffled = shuffle(mnemonic, password);

console.log(`Seedphrase: ${mnemonic}`);
console.log();
console.log(`Shuffling with password "${password}"...`);
console.log();
console.log(`Shuffled: ${shuffled}`);

Output:

Seedphrase: word1 word2 word3 word4 word5 word6 word7 word8 word9 word10 word11 word12 word13 word14 word15 word16 word17 word18 word19 word20 word21 word22 word23 word24

Shuffling with password "PASSWORD"...

Shuffled: word2 word17 word22 word6 word3 word11 word8 word19 word18 word10 word9 word4 word13 word23 word1 word14 word7 word15 word16 word12 word21 word24 word5 word20