StegCloak - Hide secrets with invisible characters in plain text securely using passwords


StegCloak is a pure JavaScript steganography module designed in functional programming style, to hide secrets inside the text by compressing and encrypting the secret before cloaking it with special unicode invisible characters. It can be used to safely watermark strings, invisible scripts on webpages, texts on social media, or for any other covert communication. Completely invisible! See how it works in-depth in this Medium article or watch our demo to know what it does.


  • Protect your invisible secret using passwords and HMAC integrity
  • Cryptographically secure by encrypting the invisible secret using AES-256-CTR.
  • Uses 6 Invisible characters in unicode characters that work everywhere on the web - Tweets, Gmail, WhatsApp, Telegram, Instagram, Facebook, and many more!
  • Maximum Compression to reduce the payload (LZ, Huffman).
  • Completely invisible, uses Zero Width Characters instead of white spaces or tabs.
  • Superfast! Hides the Wikipedia page-source for steganography (800 lines and 205362 characters) within a cover text of 3 words in under one second.
  • Hiding files in strings can be achieved by uploading the file to the cloud and stegcloaking the link in the string
  • Written in a pure functional style.
  • Usage - Available as an API module, a CLI, and also a Web Interface (optimized with web workers).


Using npm,

$ npm install -g stegcloak

Using npm (to use it locally in your program),

$ npm install stegcloak

How it works

CLI Usage


$ stegcloak hide


  hide [options] [secret] [cover]

  -fc, --fcover <file>      Extract cover text from file
  -fs, --fsecret <file>     Extract secret text from file
  -n, --nocrypt             If you don't need encryption (default: false)
  -i, --integrity           If additional security of preventing tampering is needed (default: false)
  -o, --output <output>     Stream the results to an output file
  -c, --config <file>       Config file
  -h, --help                display help for command


$ stegcloak reveal       


  reveal [message]

  -f, --file <file>       Extract message from file
  -cp, --clip             Copy message directly from clipboard
  -o, --output <output>   Stream the secret to an output file
  -c, --config <file>     Config file
  -h, --help              display help for command

Additional support

  • STEGCLOAK_PASSWORD environment variable, if set, will be used by default as a password.
  • Configuration file support to configure StegCloak CLI and to avoid prompts. Read the config docs here.

API Usage

const StegCloak = require('stegcloak');

const stegcloak = new StegCloak(true, false);  // Initializes with encryption true and hmac false for hiding

// These arguments are used only during hide

// Can be changed later by switching boolean flags for stegcloak.encrypt and stegcloak.integrity
What's HMAC and do I need it?

HMAC is an additional fingerprint security step taken towards the tampering of texts and to verify if the message received was actually sent by the intended sender. If the data is sent through WhatsApp, Messenger, or any social media platform, this is already taken care of! However, if you are using StegCloak in your program to safely transmit and retrieve, this option can be enabled and StegCloak takes care of it.


stegcloak.hide(secret, password, cover) -> string
const magic = stegcloak.hide("Voldemort is back", "mischief managed", "The WiFi's not working here!");

// Uses stegcloak.encrypt and stegcloak.integrity booleans for obfuscation

console.log(magic);  // The WiFi's not working here!


stegcloak.reveal(data, password) -> string
const secret = stegcloak.reveal(magic, "mischief managed");

// Automatically detects if encryption or integrity checks were done during hide and acts accordingly

console.log(secret); // Voldemort is back

This amazing blog by Francesco Soncina shows how you could use the StegCloak API to watermark any text on your website.


StegCloak doesn't solve the Alice-Bob-Warden problem, it's powerful only when people are not looking for it and it helps you achieve that really well, given its invisible properties around the web! It could be safely used for watermarking in forums, invisible tweets, social media, etc. Please don't use it when you know there's someone who is actively sniffing your data - looking at the unicode characters through a data analysis tool. In that case, even though the secret encoded cannot be deciphered, the fact lies that the Warden (middle-man) knows some secret communication took place because he would have noticed an unusual amount of special invisible characters.


The following papers were referred to for insight and understanding of using Zero Width Characters in steganography.

  • Milad Taleby Ahvanooey, Qianmu Li , Jun Hou, Ahmed Raza Rajput and Chen Yini
Modern Text Hiding, Text Steganalysis, and Applications: A Comparative Analysis
  • Taleby Ahvanooey, Milad & Li, Qianmu & Hou, Jun & Dana Mazraeh, Hassan & Zhang, Jing.
AITSteg: An Innovative Text Steganography Technique for Hidden Transmission of Text Message via Social Media.
IEEE Access


Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Visit the website:


MIT - Copyright (c) 2020 Jyothishmathi CV, Kandavel A, Mohanasundar M


The StegCloak logo was designed by Smashicons.

July 10, 2020
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