How Provably Fair Games Work and How to Verify a Bet
Provably fair is a method that lets you check every game result yourself. Instead of asking you to trust the casino, it gives you the data and the formula to confirm that a round was not changed after you placed your bet. This guide explains the server seed, the client seed and the nonce, then shows how to verify a bet step by step.
Why Provably Fair Matters
In a traditional online game, a random number generator runs on the operator's servers. Testing labs audit it, but you never see the inputs of your own rounds. You rely on that audit.
Provably fair systems add a second layer. They use cryptography to commit to the outcome before you bet. After the round, they reveal the inputs, so anyone can recompute the result. If the numbers match, the round was fair in the technical sense: it was fixed in advance and could not be edited later.
It is important to be clear about what this proves. It shows the result was not manipulated. It does not remove the house edge, and it does not make any outcome more likely. Every round is still random.
The Three Ingredients
Server Seed
The server seed is a long random value created by the casino. Before you bet, you are shown only its hash. A hash is a one-way fingerprint, usually made with SHA-256. You cannot work backwards from the hash to the seed. But once the seed is revealed, anyone can hash it and compare.
Showing the hash first is a commitment. The casino has locked in its seed without telling you what it is. If it changed the seed later, the hash would no longer match.
Client Seed
The client seed comes from your side. It is often generated by your browser, and you can usually replace it with any text you like. Because the casino cannot know your client seed in advance, it cannot pick a server seed that produces a chosen result.
Nonce
The nonce is a counter. It starts at zero or one and rises by one with every bet you make on the same seed pair. It makes sure each bet produces a new result, even though the seeds stay the same.
How Provably Fair Results Are Generated
A typical scheme combines all three ingredients with a keyed hash function such as HMAC-SHA256. The server seed acts as the key. The client seed and nonce form the message. The output is a long string of characters that looks random.
That output is then converted into a game result. For a dice game, the first few bytes might become a number between 0 and 100. For a crash game, they might become the multiplier at which the round ends. Each game has its own conversion step, and the exact formula should be published.
| Input | Who Controls It | When You See It |
|---|---|---|
| Server seed | Casino | Hash before betting, full value after rotation |
| Client seed | You | Always |
| Nonce | Counter | Always, rises with every bet |
The details on Aslot for each game, including the exact formula, are described on the Provably Fair page.
How to Verify a Bet Step by Step
- Note the hash. Before you start, copy the hashed server seed shown in the fairness settings.
- Set your client seed. Keep the generated one or enter your own text. Changing it gives you extra assurance.
- Place your bets. Each bet records the client seed and its nonce. You can find them in the bet details.
- Rotate the seed. When you request a new seed pair, the old server seed is revealed. Rounds played on it can now be checked.
- Check the hash. Hash the revealed server seed with SHA-256. It must match the hash you copied in step 1.
- Recompute the result. Feed the server seed, client seed and nonce into the published formula. The output must match the result of your bet.
You do not have to write code for this. Many casinos offer a built-in verifier, and independent open-source verifiers exist too. A verifier you can inspect yourself is the most trustworthy option.
Common Questions About Seeds
Why can't you see the server seed right away? Because knowing it would let you predict every upcoming result. The hash protects the game while still binding the casino to its choice.
Why rotate seeds at all? Rotation is the moment the old seed becomes public. Without it, past rounds could never be checked. Rotating regularly keeps your verification window short.
Provably fair checks fit naturally with the in-house originals on Aslot, such as dice and crash. These games are built around simple, published formulas, which makes every round easy to audit.
Play responsibly: a fair game is still a game of chance. Results are random, the house edge applies, and you should only bet what you can afford to lose.
FAQ
Does Provably Fair Mean I Will Win More?
No. Provably fair proves that results were not changed after you bet. The odds and the house edge stay exactly the same.
Can I Change My Client Seed at Any Time?
In most systems you can change it whenever you rotate to a new seed pair. The nonce then resets for the new pair.
What If the Hash Does Not Match?
A mismatch would mean the revealed seed is not the one committed to before betting. Save the bet details and contact support right away.
Are All Casino Games Provably Fair?
No. Most third-party slots use certified random number generators instead. Provably fair is most common in in-house games like dice and crash.