Provably FairExplained
How crypto casinos prove they're not cheating — and how to verify it yourself in under 60 seconds.
What Does Provably Fair Mean?
In traditional online casinos, you have to trust that the RNG (random number generator) is genuinely random and not rigged. You can't verify it — you just hope the casino isn't cheating.
Provably fair gambling uses cryptographic hashing to let you verify the outcome of every bet after the fact. Before a bet, the casino commits to a result by publishing a hash of it. After the bet, they reveal the original value. You can confirm the hash matches — proving they didn't change the outcome retroactively.
One-sentence version: the casino locks in the result before you bet, you verify the lock after — cryptography makes cheating mathematically impossible.
How It Works Step by Step
1. Server Seed
Before your session starts, the casino generates a server seed — a random string. They hash it (SHA-256) and show you the hash. They can't change the seed now without the hash changing, which you'd notice.
2. Client Seed
You provide a client seed — your own random input. This means the casino can't predict the outcome either, even if they wanted to. You can change your client seed at any time.
3. Nonce
Each bet increments a nonce (counter). This ensures every bet produces a unique outcome even with the same seeds.
4. The Result
The outcome is computed as: HMAC_SHA256(server_seed, client_seed + nonce)
This produces a number that's converted to a game result. After betting, the casino reveals the unhashed server seed. You can recalculate the hash and confirm it matches what they showed you upfront.
How to verify on Stake: Go to any completed bet → click the fairness icon → click "Verify" → the site recalculates the result from the revealed seeds and confirms it matches. Takes 10 seconds.
What Provably Fair Doesn't Guarantee
Provably fair proves the result wasn't changed after the fact. It doesn't prove:
- The house edge is what they claim — the math could still be set to 5% while they advertise 1%
- The game is fair over time — you can verify individual bets, not long-run statistical distributions
- Front-end manipulation is impossible — a rigged UI could display a different result than what was computed
- Withdrawal processing is honest — provably fair is about game outcomes only, not payout reliability
It's a strong guarantee but not a complete one. Pair provably fair with a casino that has a solid withdrawal track record.
Which Casinos Use Provably Fair?
| Casino | Provably Fair | Scope | Verify Tool |
|---|---|---|---|
Stake.com | Yes | All Stake Originals | Built-in per bet |
Rollbit | Yes | Originals + some slots | Built-in |
BC.Game | Yes | All BC Originals | Built-in |
Roobet | Yes | Roobet Originals | Built-in |
Shuffle | Partial | Select games | Built-in |
Third-party slots | No | Not applicable | Trust RNG cert only |
Note: third-party slot providers (Pragmatic, Hacksaw, BGaming) use RNG certificates from auditors like eCOGRA instead of provably fair. Different trust model — audited rather than self-verifiable.
Provably fair + no-KYC is the full package. Read our guide to staying anonymous.
No-KYC Guide →