Provably fair, round by round

  1. Sealed secretFingerprint shown first
  2. Your seedYours to change
  3. drand roundPublic, every 30 s
  4. HMAC-SHA256Mixes all three
  5. ResultRe-checkable
drand round6 584 369
randomness································
Check a round now

Every Goldrush result is made from three inputs, two of which you can see before you play and one that nobody controls. Afterwards anyone can repeat the sum and get the same answer.

Seal: the secret is fixed before you play

The server draws a secret from a cryptographically secure random generator, the same kind of generator encryption relies on. Before your round, you are shown only its fingerprint, a SHA-256 hash. The secret cannot change after that without the fingerprint giving it away. This is the commit in commit-reveal.

Mix: three inputs, one result

HMAC-SHA256 mixes the sealed secret with your own seed and the latest public number from drand, along with a counter for the round. Your seed is yours: you can change it whenever you like. The drand number comes from the League of Entropy, an international group of independent organisations that publishes a fresh, signed random value every thirty seconds. Goldrush is not part of it and cannot steer it.

Map: no result is favoured

The mixed output is read as a run of numbers and each one is turned into a result in the game's range: a reel stop, a dice roll, a path down the pins or the point where a flight ends. A number that would tilt the odds towards one result is thrown away and the next one is read, so every outcome in the range stays equally likely.

Reveal: check it yourself

Once the round settles, the secret is revealed. Hash it and you get the fingerprint you were shown. Feed the same three inputs into HMAC-SHA256 and you get the same result. The Goldrush is Provably Fair page in the app does this for any round, in your own browser, and shows the live rounds as they settle.

What this does and does not mean

Provably fair means the result was fixed before you played and you can prove it was not changed. It does not mean you will win: every game has a return to player below 100%, shown on each game page. Goldrush makes no claim of outside laboratory certification.

Browse the games or read how Gold Coins work.