Provably fair
A cryptographic method that lets you confirm a game result was set before your bet and left untouched afterwards.
Provably fair is the verification model crypto casinos use to demonstrate that an outcome was fixed ahead of time and could not be adjusted after seeing your bet. Three inputs drive it: a secret server seed from the casino, a client seed you choose, and a bet counter known as the nonce.
The four steps
- The casino commits to its secret server seed up front by publishing the seed's SHA-256 hash.
- You pick a client seed, which the casino has no way to anticipate.
- For every bet, the game computes HMAC-SHA256 keyed with the server seed over a message made from your client seed and the nonce, then maps that output to a result.
- Rotating seeds makes the casino disclose the old server seed. Hash it, confirm it equals the earlier commitment, and recompute each bet.
Limits of the proof
What you get is proof that outcomes of verifiable games match the seeds the casino committed to. It does nothing to the house edge, it does not extend to third-party slots or live dealer tables, and it is no promise that you will be paid. Each casino implements the scheme a little differently, so always verify against that casino's own published method.