OneTimePadJS

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

• Generating one-time-pads - encryption/decryption keys.
• Converting plaintext to plaincode.
• Converting plaincode to plaintext.
• Encrypting plaincode text
• Decrypting encrypoted text
• Check length of message is too long for the encryption key.
• Language conversion tables, regular expressions for plaintext <-> plaincode and codebook for emojis.

Will be core functionality together with nfc-json-transfer for creating otp-encryption-toy

Getting the script in your environment

CJS - CommonJS

const { textToPlaincode, plaincodeToText, createOnetimePad, nob, codebook, checkLength, encryptPlaincode, decryptEncryptedMsg } = require('otp-encryption-decryption-lib')

ESM - Ecmascript Modules

import { textToPlaincode, plaincodeToText, createOnetimePad, nob, codebook, checkLength, encryptPlaincode, decryptEncryptedMsg } from 'otp-encryption-decryption-lib'

Usage

index.mjs:

import { textToPlaincode, plaincodeToText, createOnetimePad, nob, codebook, checkLength, encryptPlaincode, decryptEncryptedMsg } from 'otp-encryption-decryption-lib'

// 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(''))

// ### 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')

When doing ESM-version of the library, run it with:

node --experimental-json-modules index.mjs

API

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.

plaincodeToText()

Converts plaincode back to plaintext.

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

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.

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.

decryptEncryptedMsg()

Decrypts the encrypted message with the same one-time-pad that it was encrypted with.

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

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

• 00000 - 09999: Unicode emojis

Codebook for emojis. Not language specific. Starts with a 0 in plaincode and then 4 digits. Traditionallhy it has been used to be able to write shorter messages, having a short code for longer, often used words. Here it is to be able to express all Unicode emojis.

Example of three first entries:

codebook: [
  {
    unicode: '😀',
    plaincode: 00000
  },
  {
    unicode: '😃',
    plaincode: 00001
  },
  {
    unicode: '😄',
    plaincode: 00002
  }
]

Maintenance

If unicode emojis are updated (to i.e. v.16 from v.15)

cd scipts
node ./fetch-emojis.mjs && node ./create-emoji-regex.mjs && node ./create-emoji-codebook.mjs

Possible issue

• It's an untested toy. 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 nfc-json-transfer.
• I haven't found a unique way of numbering/addressing the unicode emojis that will work cross unicode emoji versions, so then stuff won't encrypt/decrypt properly if you use different versions of the library.