FYShuffle

FYShuffle is a JavaScript-based text scrambler based on the Fisher-Yates shuffle algorithm. It is designed to obfuscate arbitrary text—primarily email addresses—so they are hidden from bots while remaining readable to users with JavaScript enabled.

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Features

• Works in both browser and Node.js environments
• Deterministic scrambling using a 31-bit numeric key
• Output is reversible with the correct key
• No external dependencies
• Distributed in multiple formats:
  • FYShuffle.js: browser-compatible UMD build
  • FYShuffle.min.js: minified UMD
  • FYShuffle.module.js: ES module for bundlers
  • FYShuffle.node.js: CommonJS build for Node

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Cryptographic Strength

Do not use FYShuffle for anything requiring actual security.

This is not a cryptographic algorithm and is not designed to resist serious attacks. The keyspace is limited (2³¹), and the shuffle is reversible. That said, for its intended use—discouraging bots—it provides practical obfuscation without exposing the original text directly.

With shorter inputs, brute-force is inefficient. With longer inputs, statistical attacks become feasible. Still, it's far more effective than leaving plain text in the DOM.

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Why Does This Work?

In theory, it shouldn’t—if a browser can unscramble the content, so can a bot. But in practice, bots don’t execute JavaScript on every page they crawl. Doing so is too resource-intensive when crawling at scale.

• Bots usually see the placeholder or scrambled data
• Human users see the original content after client-side decoding

This asymmetry is enough to meaningfully reduce spam and scraping in many real-world cases.

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Accessibility Considerations

This is not a best-practice approach to accessibility. Screen readers, text-only browsers, and users with JavaScript disabled will not see the unscrambled content.

If you use FYShuffle:

• Limit its use to cases where obfuscation is necessary
• Provide alternate access where appropriate (e.g., contact forms)
• Consider fallback content or progressive enhancement

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Usage

In the Browser

<script src="FYShuffle.js"></script>

<div class="email" data-content="obfuscatedBase64String"></div>

<script>
  mailtoClass('email', 123456); // Decodes and replaces with a <a href="mailto:...">
</script>

Other utilities include scrambleClass() and unscrambleClass() for general-purpose content.

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In Node.js

import { FYForward, FYBackward } from 'FYShuffle';

const key = 123456;
const input = 'hello@example.com';

const scrambled = FYForward(input, key);
const original = FYBackward(scrambled, key);

console.log(original); // hello@example.com

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Installation

If published to npm:

npm install FYShuffle

If working from source:

git clone https://github.com/BFGConsult/FYShuffle.git
cd FYShuffle
npm install

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Build

To generate the output bundles:

npm run build

The following files will be created in the dist/ directory:

dist/
├── FYShuffle.js         // UMD (for browsers)
├── FYShuffle.min.js     // Minified UMD
├── FYShuffle.module.js  // ESM (for bundlers)
├── FYShuffle.node.js    // CommonJS (for Node)

Use npm run build -v for verbose logging.

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Demo

Try FYShuffle live at:

https://bfgconsult.github.io/FYShuffle/

The demo lets you:

• Enter custom text and key
• See the scrambled result
• Test browser rendering of decoded content

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Project Structure

.
├── dist/                # Final build artifacts
│   ├── FYShuffle.js
│   ├── FYShuffle.min.js
│   ├── FYShuffle.module.js
│   └── FYShuffle.node.js
├── index.html           # Demo/test page
├── package.json         # Project metadata and build config
├── package-lock.json
├── README.md
├── LICENSE              # GNU Affero General Public License
├── scripts/
│   └── build.js         # Build and bundling script
└── src/
    ├── core/
    │   ├── base64.browser.js
    │   └── base64.node.js
    ├── fyshuffle-core.js
    ├── fyshuffle-crypto.js
    └── fyshuffle-dom.js