Provably fair, decoded
What a seed hash proves, what it doesn't, and how to verify a round.
"Provably fair" means the site commits to a random seed before you bet, and lets you verify afterwards that the result was derived from that seed plus one you supplied. It proves the outcome was not changed after your bet. It does not prove the odds are good.
How it works
- The server generates a secret server seed and shows you its hash (SHA-256).
- You supply (or the site assigns) a client seed; a nonce counts your bets.
- Each result is computed from HMAC(server seed, client seed + nonce), mapped to a Roll slot, a Dice number, a Crash point.
- When the server seed is rotated, the old one is revealed; you hash it and check it matches what you were shown, then recompute any past result.
What it proves
That the site could not have picked a worse result for you after seeing your bet. That the sequence of results was fixed by the seeds.
What it doesn't prove
That the payout table is fair. A provably fair Roll still pays 2× on a 46.67% chance. A provably fair case still costs 10% more than its expected value. The house edge sits in the payout table, not in the RNG — verify both.
Checking a site
Look for a "Provably fair" page with the seed hash, a way to change your client seed, and a verifier. CSGORoll, CSGOEmpire, Stake, Gamdom and 500.casino all publish one. The simulators here use your browser's cryptographic RNG instead — nothing to verify because nothing is at stake.
Glossary
- House edge
- The share of every wager the operator keeps over the long run. 1% edge = ◎10 expected loss per ◎1,000 wagered.
- RTP
- Return to player — the mirror of house edge. 90% RTP on a case means a 10% edge.
- Expected value (EV)
- What a bet is worth on average: sum of (payout × probability). Always below the stake on a real site.
- Variance
- How much results swing around the average. High variance = long dead runs, rare big hits.
- Provably fair
- A seed-hash system letting you verify a result was fixed before your bet. Proves honesty, not good odds.
- Rakeback
- A percentage of the house edge you generate, returned regardless of win or loss.
