Prize wheel access

Enter your access key. Operator keys run draws; the Super Admin key also changes the odds, prize and branding.

OPERATOR Provably Fair Prize Wheel · build 17 · server
–ready
Winner's number: not picked yet 250 segments

⚙Draw settings

Locked. Only a Super Admin can change the odds, the major prize and club branding. Operators run the draw with the settings as configured.

1Lock the draw

The draw server generates a secret random seed and returns only its SHA-256 fingerprint (the commitment) before the winner picks a number. The seed itself never reaches this screen until the draw is final.

2Winner picks a number

The winner chooses any number in the range. Their choice feeds directly into the result, so the outcome depends on both the locked seed and their pick.

3Spin

How this draw is provably fair
  1. Seed. A 32-byte seed is generated on the draw server by a cryptographic random number generator (crypto.randomBytes). It is never chosen by a person and never leaves the server until the draw is final.
  2. Commitment. Before the winner picks anything, the page displays SHA-256(seed). Publishing this fingerprint first makes it impossible to swap the seed later: any change to the seed changes the fingerprint.
  3. The pick. The winner chooses a number. Because the seed was locked first, the operator cannot steer the result; because the pick feeds into the result, the winner directly influences it. Neither side controls the outcome alone.
  4. Result. The landing number is computed as SHA-256(seed + ":" + range + ":" + pick), read as a 256-bit integer and reduced to the range with rejection sampling (no modulo bias: if the integer falls in the tiny biased tail above floor(2^256 / N) × N, it is re-hashed; the odds of even one re-hash are about 1 in 1074). Result = remainder + 1.
  5. Reveal. After the spin the seed is displayed. Anyone can recompute both hashes and confirm the wheel had no choice but to land where it did. The wheel animation is theatre; the number is fixed by the maths the moment the winner picks.

Each draw is one-shot and the SERVER enforces it: the draw is finalised and logged the instant the pick is accepted, before the wheel even starts turning, and a second pick against the same commitment is rejected. This page is presentation only; it cannot influence or re-run a result.

Verify a past draw

Paste the revealed seed, the range and the winner's pick from any draw. This recomputes the commitment and the landing number from scratch. It will match any independent SHA-256 implementation.

Draw log (this device)

Every commitment and result is recorded on the draw server in an append-only, hash-chained log: each record embeds the cryptographic fingerprint of the record before it, so any edit or deletion of history breaks the chain and is detected. Nothing here can be cleared from the browser.

WhenPromotion / winnerRangePickLandedResultCommitmentSeed