Education 6 min read

What is Provably Fair Gaming? A Complete Guide

Learn how provably fair algorithms ensure transparent and verifiable game outcomes in crypto casinos. Understand the cryptography behind fair gaming.

By MPlay Team • January 3, 2025

If you've explored crypto casinos, you've probably seen the term "Provably Fair" everywhere. But what does it actually mean? How can you verify that a game is truly fair? In this guide, we'll break down the technology that makes provably fair gaming possible.

The Problem with Traditional Online Casinos

Traditional online casinos operate as black boxes. When you spin a slot or play blackjack, you're trusting the casino's claim that their Random Number Generator (RNG) is fair. You have no way to verify this yourself—you simply have to trust them.

This creates an obvious problem: how do you know the house isn't cheating?

Provably fair gaming solves this by using cryptographic techniques that allow anyone to verify game outcomes independently.

ℹ️ Key Difference

Traditional casinos ask you to trust them. Provably fair casinos give you the tools to verify for yourself.

How Provably Fair Works

The core concept is simple: before any game round, the casino commits to an outcome that it cannot change later. Here's the process:

1. Server Seed Generation

Before you place a bet, the casino generates a Server Seed—a random string of characters. This seed determines the game outcome. But here's the key: instead of showing you the seed directly (which would let you predict the result), the casino shows you a hash of the seed.

Server Seed: a3f8c2e1...
Hash (SHA-256): 7b4d9e2a8f1c3b5d...

A hash is a one-way function. You can verify that a seed produces a specific hash, but you cannot reverse-engineer the seed from the hash. This is how the casino commits to an outcome without revealing it.

2. Client Seed Input

You provide a Client Seed—a string of your choosing. This ensures you have influence over the outcome. Combined with a Nonce (a counter that increases with each bet), each game round produces a unique result.

3. Outcome Calculation

The game result is calculated using a cryptographic function:

Result = HMAC-SHA256(ServerSeed, ClientSeed + Nonce)

This produces a deterministic outcome—the same inputs always produce the same output.

4. Verification

After the round ends, the casino reveals the Server Seed. You can now:

Hash the revealed Server Seed and confirm it matches the hash shown before the game
Run the HMAC function yourself and verify the game outcome was calculated correctly

MPlay provably fair verification screen showing seeds and hash — The verification screen on MPlay - check any bet's fairness with the server seed, client seed, and nonce

Why This Matters

Provably fair gaming provides several key benefits:

Transparency — Every outcome can be independently verified
No Manipulation — The casino cannot change outcomes after committing
Player Influence — Your client seed affects the result
Trustless — You don't need to trust the casino; you can verify

✅ The Power of Verification

With provably fair gaming, you can verify every single bet you've ever made. If even one bet was manipulated, you would be able to prove it mathematically.

Verifying Your Bets on MPlay

On MPlay, every game is provably fair. To verify a bet:

Go to your Game History
Click Verify on any completed bet
Copy the Server Seed, Client Seed, and Nonce
Use any online HMAC-SHA256 calculator to confirm the result

Or visit our Fairness page for detailed technical documentation.

💡 Pro Tip

Change your client seed periodically. While the server seed is already random, using your own unique client seed adds an extra layer of control.

Conclusion

Provably fair gaming represents a fundamental shift in online gambling. By leveraging cryptography, crypto casinos like MPlay can offer something traditional casinos never could: mathematical proof that games are fair.

Don't just trust—verify.