Provably fair verifier
Check that a casino did not change a result after you bet. Paste the revealed server seed, your client seed and the nonce: the verifier confirms the seed matches the hash you were shown before playing, then recomputes the result. Everything runs in your browser; nothing is sent anywhere.
What the verifier checks
- The commitment. Before you play, the casino shows you the SHA-256 hash of its server seed. After you rotate seeds, it reveals the seed itself. If SHA-256 of the revealed seed equals the hash you were shown, the casino could not have swapped the seed in between.
- The round hash. Each result comes from HMAC-SHA256, keyed with the server seed, over your client seed and the nonce joined by a colon (for example myseed:42). The nonce counts your bets with that seed pair, starting at 0.
- The result. The hash is turned into a game outcome with a fixed formula. Re-running it must give exactly the result in your bet history.
How each Lumenbet game turns the hash into a result
| Game | Formula | House edge |
|---|---|---|
| Dice | First 13 hex characters as a number, modulo 10,000, divided by 100: a roll from 0.00 to 99.99 | 2% |
| Limbo | First 8 hex characters as v: 232 / v × 0.98, between 1x and 1,000x | 2% |
| Coinflip | First 8 hex characters: even is heads, odd is tails | 1% |
| Crash | HMAC of the round's server seed over the round number; first 8 hex characters as h: 232 / (h + 1) × 0.97, between 1x and 1,000x | 3% |
| Mines | Each 8-character chunk picks a tile from those left on a 25-tile board; the hash is re-hashed when it runs out | 2% |
| Plinko | Each 8-character chunk is one row: even falls left, odd falls right. Above 8 rows a second hash (nonce followed by :1) extends it | 2% |
| Keno | Both hashes drive a shuffle of 1 to 40; the first 10 numbers are drawn | 4% |
Crash is different from the other games because every player shares the same round. Its seed belongs to the round, not to you: verify it with the round seed and round number shown in that round's details.
When verification fails
- Check the inputs first. A trailing space, a different nonce or the wrong client seed changes every result. Copy the values straight from the casino's fairness page.
- Nonce off by one. The nonce shown next to a bet is the one it used. The first bet with a seed pair uses nonce 0.
- Seed still active. You can only verify after the server seed is revealed, which happens when you rotate your seed. Mines games in progress block rotation, so finish them first.
- If it still fails, save the seeds, nonce and bet ID and contact the casino's support. A genuine mismatch is serious and should be explained.
For the background, read our guide to provably fair casinos and how Crash works.
FAQ
Does this verifier work for Stake or BC.Game?
The seed commitment and HMAC checks work for any casino using SHA-256 and HMAC-SHA256. The game results use Lumenbet's formulas; other casinos convert the hash into results differently, so use their own verifier for those.
Is it safe to paste my seeds here?
Yes. Revealed seeds are no longer secret, and the verifier runs entirely in your browser without sending anything. Never paste a seed that is still active.
Does a passed check mean the game is fair to me?
It proves the result was fixed before you bet and not changed. It does not change the house edge, which is built into each game's payouts.