otp-encrypt-js

One-time pad encryption and decryption library for the browser.

Library of helper-functions for encrypting and decrypting messages with OTPs - One-time pads.

Demo

It shows all the steps for encrypting and decrypting a message. You can check out the demo yourself: otp-encrypt-js demo

Getting the script in your environment

ESM - Ecmascript Modules

Will only work in the browser. Using it directly in an HTML file

<script type="module">
  import { textToPlaincode, plaincodeToText, createOnetimePad, nob, codebook, checkLength, encryptPlaincode, decryptEncryptedMsg } from 'otp-encrypt-js'
  // Your app here
</script>

Or you can import it from another JavaScript module:

import { textToPlaincode, plaincodeToText, createOnetimePad, nob, codebook, checkLength, encryptPlaincode, decryptEncryptedMsg } from 'otp-encrypt-js'

Usage

Encryption

import { plaincodeToText, createOnetimePad, nob, codebook, checkLength, encryptPlaincode } from 'otp-encrypt-js'

// The message
const txt = 'Hello 👨‍👩‍👦‍👦🏳️‍🌈😀🇿🇼  world 123 æøå!'
console.log('\n\nInput:               ' + txt)

// ### Text to plaincode
const plaincodeConverted = textToPlaincode(txt, nob, codebook)
console.log('Plaincode:           ' + plaincodeConverted)

// ### Creating a one-time pad
const otp = createOnetimePad(96)
console.log('One-time pad:        ' + otp)

// ### Checking length of plaincode vs. one-time pad
const lengthObj = checkLength(plaincodeConverted, otp)
console.log('Length:              ' + JSON.stringify(lengthObj))

// ### Encrypting plaincode
const encryptedMsg = encryptPlaincode(plaincodeConverted, otp)
console.log('Encrypted plaincode: ' + encryptedMsg.join(''))

Decryption

import { textToPlaincode, decryptEncryptedMsg, nob, codebook } from 'otp-encrypt-js'

// ### otp - onetime pad the same as for encrypting the message
// ### Decrypting encrypted message
const decryptedPlaincode = decryptEncryptedMsg(encryptedMsg.join(''), otp)
console.log('Decrypted plaincode: ' + decryptedPlaincode.join(''))

// ### Plaincode to text - The message delivered!
const textConverted = plaincodeToText(decryptedPlaincode.join(''), nob, codebook)
console.log('Decrypted msg:       ' + textConverted + '\n\n')

API

Encrypting a mesaage

createOnetimePad()

The length of the should be equal to or larger than your plaincode. And it should only be used once. This ensures that it is impossible to break the code and read the encrypted message.

createOnetimePad(length)
// Returns a one-time pad of desired length, as a string of digits.

textToPlaincode()

Converts plaintext to plaincode. Plaincode is just numbers, and not encrypted. It's a step that uses a conversion table to change the text, numbers and emojis into numbers, which makes it possible to do one-time pad encryption.

textToPlaincode(text, conversionLanguage, codebook)
// Returns plaincode string from a string of text.

checkLength()

Helper function to check if plaincode length (and thus your message length) is too long, and also show the user how close they are to exceed length of one-time pad.

checkLength(plaincode, otp)
// Returns { plaincodeLength: plaincodeLength, otpLength: otpLength, tooLong: tooLong }

encryptPlaincode()

Encrypt the plaincode using a one-time pad.

encryptPlaincode(plaincode, otp)
// Returns encrypted message as an string of digits. This is the encrypted message.

Decrypting a message

decryptEncryptedMsg()

Decrypts the encrypted message with the same one-time pad that it was encrypted with. You'll need the one-time pad (otp) you used to encrypt the message.

decryptEncryptedMsg(encryptedMsg, otp)
// Returns message as a string of digits - The message in plainccode.

plaincodeToText()

Converts plaincode back to plaintext.

plaincodeToText(plaincode, conversionLanguage, codebook)
// Returns text string from plaincode string.

Both needed for encrypting and decrypting messages

Language conversion tables, regular expressions and codebook.

Each language contains variables for conversion tables and regular expressions. Most used letters differs from language to language. To be able to keep the plaincode short and thus needing shorter one-time pads, the five most used letters are assigned to 0-5 in plaincode. Numbers starts with the digit 9 and consists of 3 digits.

The table is used for converting letters, digits and emojis to plaincode and the other way around. There are two regular expressions for each language. One is to split up text strings containing text, numbers and emojis into single letters, digits and emojis. The other one is to split up a plaincode-string into an array of plaincodes so that you it can use the conversion table to get a plaincode-string to a text-string (text, numbers and emojis).

For each language three variables/arrays are available

[language-code].table
[language-code].textRegex
[language-code].plaincodeRegex

Language codes

• eng - English
• nob - Norwegian

If you need it we can helpo add more languages.

Layout of conversion table

• 00000 - 09999: Codebook, which consists of Unicode emojis
• 1 - 5: 5 most used letters for this language
• 60 - 89: Other letters and symbols
• 900 - 909: Numbers from 0-9
• 91 -99: More symbols

[language-code].table

Example from eng. It differs from each language depending on the what's the most used letter, and how many letter the alphabet consists of.

table: [
    { unicode: 'a', plaincode: '1' },
    { unicode: 'e', plaincode: '2' },
    { unicode: 'i', plaincode: '3' },
    { unicode: 'n', plaincode: '4' },
    { unicode: 'o', plaincode: '5' },
    { unicode: 't', plaincode: '60' },
    { unicode: 'b', plaincode: '61' },
    { unicode: 'c', plaincode: '62' },
    { unicode: 'd', plaincode: '63' },
    { unicode: 'f', plaincode: '64' },
    { unicode: 'g', plaincode: '65' },
    { unicode: 'h', plaincode: '66' },
    { unicode: 'j', plaincode: '67' },
    { unicode: 'k', plaincode: '68' },
    { unicode: 'l', plaincode: '69' },
    { unicode: 'm', plaincode: '70' },
    { unicode: 'p', plaincode: '71' },
    { unicode: 'q', plaincode: '72' },
    { unicode: 'r', plaincode: '73' },
    { unicode: 's', plaincode: '74' },
    { unicode: 'u', plaincode: '75' },
    { unicode: 'v', plaincode: '76' },
    { unicode: 'w', plaincode: '77' },
    { unicode: 'x', plaincode: '78' },
    { unicode: 'y', plaincode: '79' },
    { unicode: 'z', plaincode: '80' },
    { unicode: ',', plaincode: '84' },
    { unicode: '@', plaincode: '85' },
    { unicode: '#', plaincode: '86' },
    { unicode: '+', plaincode: '87' },
    { unicode: '-', plaincode: '88' },
    { unicode: '/', plaincode: '89' },
    { unicode: '0', plaincode: '900' },
    { unicode: '1', plaincode: '901' },
    { unicode: '2', plaincode: '902' },
    { unicode: '3', plaincode: '903' },
    { unicode: '4', plaincode: '904' },
    { unicode: '5', plaincode: '905' },
    { unicode: '6', plaincode: '906' },
    { unicode: '7', plaincode: '907' },
    { unicode: '8', plaincode: '908' },
    { unicode: '9', plaincode: '909' },
    { unicode: '.', plaincode: '91' },
    { unicode: ':', plaincode: '92' },
    { unicode: '\'', plaincode: '93' },
    { unicode: '!', plaincode: '94' },
    { unicode: '(', plaincode: '95' },
    { unicode: ')', plaincode: '96' },
    { unicode: '=', plaincode: '97' },
    { unicode: '?', plaincode: '98' },
    { unicode: ' ', plaincode: '99' }
  ]

[language-code].textRegex

Example from eng. It differs a little bit for each language.

eng.textRegex: '[a-z0-9\\s]|[,@#+-/.:\'!(=?)]'

[language-code].plaincodeRegex

Example from eng which for latin character based languages should be mostly the same.

eng.plaincodeRegex: '0\\d{4}|[1-5]|(90[0-9]{1})|(6[0-9]{1})|(7[0-9]{1})|(8[0-9]{1})|(9[1-9]{1})'

codebook

• 000001 - 099999: Unicode emojis

Codebook for emojis. Not language specific. Starts with a 0 in plaincode and then 5 digits. Traditionally it has been used to be able to write shorter messages, having short codes for longer, often used words. Here it is to be able to express all Unicode emojis.

Example of three first entries:

const codebook = [
  {
    "id": "000001",
    "emoji": "😃"
  },
  {
    "id": "000002",
    "emoji": "😀"
  },
  {
    "id": "000003",
    "emoji": "😄"
  }
]

Dev setup

Live Preview

Install VSCode plugin: Live Preview by Microsoft and use VSCode port forwarding.

shift + command + p

Live Preview: Start Server
Live Preview: Start Server Logging

Under ports tab in server logging window, set port forwarding on port 3000

Testing

npx playwright test
  Runs the end-to-end tests.

npx playwright test --ui
  Starts the interactive UI mode.

npx playwright test --project=chromium
  Runs the tests only on Desktop Chrome.

npx playwright test example
  Runs the tests in a specific file.

npx playwright test --debug
  Runs the tests in debug mode.

npx playwright codegen
  Auto generate tests with Codegen.

Issues

• It's an untested librar. Don't bet your life on it. But it can be used to teach kids and minors about the importance of encryption. Discussion about the library and one-time pad encryption on Reddit.
• Exchanging one-time pads is a problem. May be tackled with webrtc-p2p-json-transfer.