Entropy Guard 🔐

A simple, transparent password strength checker built with Node.js

This tool evaluates password strength using entropy calculations and basic heuristics — with a strong focus on privacy, clarity, and auditability.

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✨ Features

• 🔢 Entropy-based strength calculation
• ⚡ Real-time password analysis
• 🧠 Strength classification (Very Weak → Very Strong)
• ⏱️ Time-to-crack estimation (offline GPU vs online attack models)
• 🎨 Visual strength meter (real-time UI feedback)
• 👁️ Password visibility toggle
• 🔍 Character set detection (lowercase, uppercase, numbers, symbols)
• 🚫 No password storage or logging
• 🧾 Clean and readable codebase for easy auditing

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🧠 How It Works

Password strength is estimated using entropy:

entropy = length × log2(charset_size)

Where:

• length = number of characters in the password
• charset_size = pool of possible characters used

Example

A password using:

• lowercase (26)
• uppercase (26)
• numbers (10)
• symbols (~32)

→ total charset ≈ 94

Higher entropy = harder to crack.

Time-to-crack estimation

The system estimates how long it would take to brute-force a password using:

• Offline attack (high-speed GPU cracking simulation)
• Online attack (rate-limited login attempts)

This is based on:

guesses = 2^entropy

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📊 Strength Levels

Entropy (bits)	Strength
< 28	Very Weak
28 – 35	Weak
36 – 59	Reasonable
60 – 127	Strong
≥ 128	Very Strong

Strength is now visualized in the UI using a dynamic strength bar for faster feedback.

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🚀 Getting Started

1. Clone the repository

git clone https://github.com/aiadam36/EntropyGuard
cd EntropyGuard

2. Install dependencies

npm install

3. Run the server

npm start

Server will start on:

http://localhost:3000

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🌐 Usage

1. Open the client UI
2. Enter a password
3. View entropy and strength in real-time

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🔒 Privacy First

• Passwords are never stored
• No database involved
• No external API calls
• All calculations are done locally within the app

This project is designed to be fully inspectable and safe to use.

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⚠️ Disclaimer

Entropy alone does not guarantee security.

This tool does not:

• Check against large breach databases
• Detect all common password patterns
• Replace proper security practices

Use it as a guideline, not a guarantee.

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🤝 Contributing

Contributions are welcome.

If you'd like to improve this project:

• Fork the repo
• Create a feature branch
• Submit a pull request