Provably Fair

The scheme solves the core trust problem of online dice: you cannot watch the random number generator. Instead of asking you to trust an audit, the site makes cheating detectable. It commits to a secret server seed by publishing its SHA-256 hash, then mixes that secret with a value you control (the client seed) and a bet counter (the nonce).

Because the hash was published first, the site cannot swap the server seed after seeing your bets without the hash mismatching. Because your client seed enters the mix, the site could not pre-compute a losing sequence for you before it knew your input. The result is a game where rigging a single roll leaves permanent, checkable evidence.

1. Commit. The casino generates a random server seed (usually 64 hex characters) and displays only its SHA-256 hash in your fairness settings.
2. Contribute. You set or accept a client seed. From this moment the seed pair is locked and the nonce starts at 0.
3. Play. Every bet computes HMAC-SHA256 with the server seed as key and clientSeed:nonce as message. The first bytes of that hash convert to a roll between 0.00 and 99.99. The nonce increments by one each bet, so one seed pair produces a fixed, pre-determined sequence of rolls.
4. Reveal. When you rotate to a new seed pair, the site publishes the old server seed in plain text.
5. Verify. You hash the revealed seed and confirm it matches the original commitment, then recompute any roll from the sequence.

The full walkthrough with worked hashes is in our guide to how provably fair dice works.

Verification takes under a minute. First rotate seeds in the site fairness menu, which reveals the retired server seed. Then run two checks:

• Commitment check: SHA-256 the revealed server seed. It must equal the hash you were shown before betting.
• Roll check: recompute HMAC-SHA256(server seed, client seed:nonce) for the bet in question and convert it to a roll number.

You can do this with a few lines of Python or paste the three values into our free provably fair dice verifier, which recomputes the hash chain in your browser and flags any mismatch. If even one recomputed roll differs from your bet history, you have hard proof of tampering, which is exactly the pressure that keeps operators honest.

The most common misconception is that provably fair means you cannot lose. The math is untouched: a 1% house edge applies to every verified roll, so expected loss is still 1% of total turnover. Fair and favorable are different things.

Provably fair also says nothing about the business behind the game. A site can run flawless cryptography and still delay withdrawals, confiscate balances under vague bonus terms, or disappear. Treat seed verification as one requirement among several: check licensing, withdrawal reputation, and edge before depositing anywhere.