Provable fairness
How to verify a hand
Every hand's deck comes from a seed. You see the seed hash before the first action and the seed itself after the hand ends: rebuild the deck and compare.
Four steps
Every deck comes from a random seed by a fixed rule. The server commits to the seed in advance and reveals it afterwards, so the cards cannot be swapped once you have looked at yours.
- Before the first action the server shows the seed hash — a commitment that does not reveal the seed.
- Cards are dealt from the deck derived from that seed: the same seed always gives the same deck.
- When the hand ends the seed is revealed and stored with the board, the actions and the showdown.
- Anyone can rebuild the deck from the seed and compare it with what they saw at the table.
Hand records are linked by a hash chain: a past hand cannot be edited without re-signing every hand after it. A self-check page with a “paste the seed and hand number” field is the next step.
Where such schemes break
The seed is revealed only after the hand ends. Revealing it earlier lets a player work out opponents’ cards and the rest of the deck. That defeats the whole scheme, it is not a minor detail.
A fresh seed for every hand. One seed per session means that once a player learns it after the first hand, they can predict all the following ones.
Opponents' cards never leave the game server before showdown: not into a log, not into a response, not into an error message. Enforced by a test, not by trust.