Secure Password Generator

A modern, minimal, single-file web app to generate strong passwords and test yours locally — no servers, no tracking. Built with only HTML, CSS, and vanilla JS.

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Features

• Password Generator

  • Input optional word/phrase, number seed, and symbols.
  • Control character length (4–64).
  • Choose character sets: lowercase, uppercase, digits, symbols.
  • Uses crypto.getRandomValues for cryptographically strong randomness.
  • Generated password is always exactly the requested length.
  • Smart handling if seeds exceed length (scramble/trim).

• Password Display

  • Password shown in large, selectable text.
  • Copy to clipboard button with success animation.
  • Regenerate with same settings.

• Strength & Crack-Time Analysis

  • Entropy calculation: entropy = length * log2(pool_size).

  • Detects user-supplied dictionary words and applies entropy penalty.

  • Estimates crack times for:

    • Online attack (10^4 guesses/sec)
    • Offline GPU attack (10^10 guesses/sec)

  • Displays human-friendly times (seconds → centuries).

  • Strength meter (Weak → Very Strong).

  • Short, helpful explanations.

• Password Tester

  • Paste your own password for analysis.
  • Shows entropy, strength, crack-time breakdown.
  • Suggestions for improvement (length, variety, avoiding common words).

• UX & Accessibility

  • Responsive (mobile-first) design.
  • Keyboard accessible controls.
  • ARIA live regions for updates.
  • Minimal, cozy design with rounded corners, subtle shadows, and micro-animations.
  • High-contrast friendly.

• Privacy & Security

  • Everything runs 100% locally in your browser.
  • No external fonts, icons, or libraries.
  • No network requests — nothing leaves your device.

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Tech Notes

• Randomness: Generated with window.crypto.getRandomValues.

• Entropy Formula: H = L * log2(N), where:

  • L = password length
  • N = size of character pool

• Crack Time Formula: T = (2^H) / R, where:

  • R = guesses per second (e.g., 10^4 or 10^10)
  • Assumes brute force (no smarter attacks).

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Usage

1. Open index.html in any modern browser (no server required).
2. Customize your generator settings.
3. Click Generate Password.
4. Copy your password, check its strength, and adjust as needed.
5. Test your own password in the tester box.

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Development

• All code is contained in a single index.html file.
• Written with readable ES6 and inline comments.
• No build tools, no dependencies.

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License

MIT License — use freely, but security is your own responsibility.

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⚡ Note

This project is educational and practical, but no tool can guarantee perfect security. Always combine strong passwords with good security hygiene (2FA, password managers, unique passwords per site).