Lottery Fairness Verifier

Loading Bcrypt Library

Please wait a moment...

Server Seed (Revealed After Draw)

Commit Hash (Bcrypt Hash Published Before Draw)

Server Seed (Input):

Commit Hash (Bcrypt):

💡 How to Use This Verifier: Enter the Server Seed (revealed after the lottery ended) and the Commit Hash (bcrypt hash published before the draw).

The system will cryptographically verify that the commit hash was correctly generated from the server seed using bcrypt algorithm.

URL Parameters Support: ?serverSeed=YOUR_SEED&commitHash=YOUR_HASH

📝 Load Example Data

⚠️ Performance Notice: Bcrypt verification may take 5-30 seconds depending on the rounds used (typical systems use 10-15 rounds). This computational intensity is intentional and ensures cryptographic security.

Don't Trust, Verify!

This verifier is 100% open-source and runs entirely in your browser. No data is ever sent to any server. All verification happens locally on your device.

GitHub Source How It Works

💡 Security Tip: Download this HTML file and run it completely offline. The verification works without any internet connection after the bcrypt library loads.

🔐 Core Verification Logic

async function verifyFairness() {
  // 1. Get user inputs
  const serverSeed = document.getElementById("serverSeed").value;
  const commitHash = document.getElementById("commitHash").value;
  
  // 2. Use bcrypt.compare() to verify
  // This cryptographically checks if:
  // bcrypt.hash(serverSeed) === commitHash
  const isValid = await bcrypt.compare(serverSeed, commitHash);
  
  // 3. Display the result to user
  displayResult(isValid, serverSeed, commitHash);
}

🛡️ Security & Privacy Features

100% Client-Side: All verification happens in your browser, nothing is sent to any server
Zero Server Communication: Your lottery data never leaves your device
Open Source & Auditable: You can inspect and verify every line of code
Bcrypt Algorithm: Industry-standard cryptographic hashing (used by major platforms)
Offline Capable: Works completely offline after initial library load
No Analytics or Tracking: No cookies, no tracking, complete privacy

🔍 How to Independently Verify This Code

Press Ctrl+U (or Cmd+U on Mac) to view the page source
Search for bcrypt.compare to see the exact verification logic
Compare with the GitHub repository
Download this file and run it offline on your local machine
Inspect the Network tab in DevTools - you'll see no data is sent anywhere

            ⚡ Quick Verification Method:
            
            Right-click anywhere on this page → "View Page Source" → Search for
            "bcrypt.compare"
            
            You'll see the exact code that performs the cryptographic
            verification. That's all there is to it!

🎯 Provably Fair Explained

Provably Fair is a cryptographic technique that allows you to verify the fairness of a lottery or game without trusting the operator.

How it works:

Before the draw: Operator publishes a cryptographic hash (commit hash)
Tickets are sold: Users buy tickets with the hash visible
After the draw: Operator reveals the server seed
Verification: Anyone can verify that hash(server_seed) = commit_hash

This proves the operator couldn't have changed the server seed after seeing the tickets, ensuring complete fairness.