Fair Play

In one sentence

A fair casino cannot change a result after seeing your bet. In DUBO, the server commits to a secret seed before you play, mixes it with a seed of your own and a bet counter to draw every result, and lets you reveal the secret later to check every round it dealt.

How it works

1. 1

   DUBO picks a secret seed

   A random 32-byte server seed is made for your account, and we show you its SHA-256 fingerprint right away: a hash you can see, which reveals nothing about the seed itself but pins it down.

2. 2

   You add your own seed

   Your client seed is any text you like, and you can change it at any time. Every round also has a number, the nonce, which goes up by one with each bet.

3. 3

   The three make the result

   The random numbers of a round are HMAC-SHA256 of the server seed over 'client seed : nonce : cursor', read as numbers between 0 and 1. The game turns them into the pocket of the wheel, the cards or the crash point, following the rules written on the table's easel.

4. 4

   Reveal and check

   When you reveal your server seed, we show it and start a new one. The fingerprint you were shown proves it was the seed in use all along. With that seed, your client seed and a bet number, anyone can recompute every number of every past round.

Check a bet yourself

1. 1

   Open Fairness

   The Fair tab of the account page, or of the in-game tablet, shows the fingerprint of your current secret seed, your client seed and the number of bets made with them.

2. 2

   Reveal DUBO's seed

   Press Reveal DUBO's seed. The seed behind your past bets appears, a fresh secret seed is locked in for your next bets, and the bet number goes back to 0.

3. 3

   Pick a bet

   In Activity, open any bet made with the revealed seed and press Check, or type the seeds and the bet number into the checker at the bottom of the Fair tab.

4. 4

   Read the result

   The checker confirms that the revealed seed matches the fingerprint you were shown and lists the random numbers the round used. It runs in your browser, offline too.

Open Fairness in my accountMy bets

Shared tables

At the giant VIP tables, on Sky Jump's flight and at the Showtime stage, every player bets on the same round. Those rounds use one seed per round: its hash is shown before the bets open and the seed is revealed with the result, so every player's game replays the round and shows VERIFIED when the numbers match.

The server decides, and says what it pays

• No draw, payout, purchase or balance is ever decided in your browser. What you see is a replay of what the server did.
• Every table shows its rules and its return to player on the easel beside it. Every game's return is declared in the code and checked by tests against exact maths or long simulations.
• Returns sit between 95 % and 97.5 % for most games. Blackjack, baccarat and craps keep their traditional rules and pay more.
• Every game has a maximum win of 10,000 times the stake, and a round never pays more than $250,000 in play chips; the progressive jackpots of the slots are capped the same way.
• Chip movements are written to an append-only ledger whose rows are chained by hash, so a change to history would show.

The complete sheet of every game, option by option, is published with the game's documentation and will be part of the certification file.

What fair play asks of you

Fair goes both ways: no bots, no exploits, no tampering with the client. If you find a bug, tell us instead of using it. Rounds affected by a bug are voided and balances restored, and the Terms say the rest.

Independent review

DUBO has not yet been certified by an independent testing laboratory. The file a lab needs, with the random number generation report, the rules and return sheets of every game, the game history and the security notes, is written and will be submitted before any real-money play. Until then, you have the checker.