Seed phrase + secret for preventing hack, PoC

seed-phase-secret.js

const phrase = "A B C D E F G H I J K L" 
const secret = "helloworld123"

console.log(`Phase = ${phrase}`)
console.log(`Secret = ${secret}`)
console.log(`Phase + Secret = ${encode(phrase, secret)} (<-- note this on paper)`)

if (phrase !== decode(encode(phrase, secret), secret)) {
  console.log("ERROR")
}


// ------------------------

function encode(phrase, secret) {
   const swapList = _generateSwapList(secret)
   const seeds = phrase.split(' ')
   for (let i = 0; i < swapList.length; i += 2) {
      const temp = seeds[swapList[i]]
      seeds[swapList[i]] = seeds[swapList[i+1]]
      seeds[swapList[i+1]] = temp
   }
   return seeds.join(' ')
}

function decode(encodedPhrase, secret) {
   const swapList = _generateSwapList(secret)
   const seeds = encodedPhrase.split(' ')
   for (let i = swapList.length - 1; i >= 0; i -= 2) {
      const temp = seeds[swapList[i]]
      seeds[swapList[i]] = seeds[swapList[i-1]]
      seeds[swapList[i-1]] = temp
   }
   return seeds.join(' ')
}

function _generateSwapList(secret) {
  const list = secret.split('').map(x => x.charCodeAt() % 12)
  if (list.length % 2 === 1) {
    list.push(list[list.length - 1])
  }
  return list
}