Server seed

The server seed is the casino's half of the randomness in a provably fair system. It is kept secret while you play and revealed only after you rotate to a new one.

Why it must stay secret

If you knew the server seed while it was active, you could compute every upcoming result and only bet when you would win. So the casino shows you only its hash during play.

Why it must be committed

If the casino could change the server seed after seeing your bets, it could choose a seed that makes you lose. Publishing the SHA-256 hash before play prevents that, because no one can find a different seed with the same hash.

What to do with it

After rotation, copy the revealed server seed, compute its SHA-256 hash, and compare it with the hash you were shown before playing. If they match, use the seed with your client seed and nonces to recompute your results in a verifier.

Worked example

Before play, the casino shows hash 9f86d0... You play 200 bets, rotate, and receive the seed. Hashing it gives 9f86d0... The commitment holds.