Provably fair
Provably fair is a commit-and-reveal method that lets a player check, after the round, that a game result came from inputs the operator had locked in before the bet was placed. The casino publishes a hash of its secret seed in advance, so it cannot swap the seed once it has seen your wager. What it proves is narrow, and that matters.
How a provably fair result is calculated
Three inputs go in: a server seed generated by the operator, a client seed the player can usually edit, and a nonce, a counter that rises by one with each bet under the same seed pair. Most implementations run them through HMAC-SHA256, with the server seed as the key, and the game then converts the resulting string into a dice roll, a card or a crash multiplier.
The conversion step is where practice varies between operators, so verifying a round needs that site’s own documented method.
Players meet all this in a fairness or seed panel. Once the seed pair is rotated, the old server seed is revealed, and anyone can hash it to confirm it matches the commitment shown earlier, then recompute each result.
Provably fair versus a certified RNG
The term is most often confused with RNG certification, where an accredited testing lab examines a generator before release. The rows below set out what each one actually covers.
| Question | Provably fair | Certified RNG | Practical note |
|---|---|---|---|
| Who checks | The player | A testing lab | Different kinds of trust |
| Scope | One round | Statistical behaviour overall | Neither replaces the other |
| Confirms RTP | No | Yes, against stated figures | House edge stays the same |
| Typical games | Dice, crash, plinko | Slots, table games | Complex slots rarely qualify |
| Confirms payment | No | No | That depends on the operator |
What a matching hash does not prove
A matching hash shows the result was fixed before your bet and was not altered afterwards. It says nothing about whether the house edge is fair, whether winnings will be paid, or whether the operator holds any licence. A run of losses that verifies perfectly is still a run of losses, because each round is independent and no game is ever due a win.
Verification proves integrity, not generosity.
