Verify a Draw

Do not take our word for it. Every provably fair draw publishes a sealed commitment before the wheel spins and reveals its seed afterwards — so you can recompute the result yourself and confirm the winner came from the seed, not from somebody picking a name.

  • Checked in your browser
  • No login, no lookup
  • Plain SHA-256 you can redo
How it works

Why this proves something

A result you are simply shown proves nothing — the site could have picked any name and told you it was random. Commit–reveal fixes that by making us tie our hands before we know who the entrants matter to.

1
We commit, before the spin. A secret server seed is generated and we publish only its SHA-256 fingerprint. Publishing the fingerprint locks in the seed without revealing it — a hash cannot be worked backwards, and no other seed produces the same fingerprint.
2
The draw uses that seed. The winning position is derived from SHA256(serverSeed:clientSeed:nonce:0). Nothing else influences it.
3
We reveal, after the spin. The seed is published in the receipt. You hash it and compare with the fingerprint from step 1. If they match, that seed existed before the draw — it cannot have been chosen to suit the outcome.
4
You redo the maths. The same seed, entrants and weights must produce the same winner. If they do, the result was fixed by the seed the moment we committed to it.

Check it without us

This page runs in your browser, but you do not have to trust that either. Every value in a receipt is a plain SHA-256 digest of a plain string, so you can reproduce both steps in any hashing tool:

  • The commitment: hash the serverSeed exactly as it appears. It must equal the published commitment.
  • The draw: hash serverSeed:clientSeed:nonce:0 — the seeds joined by colons. The first four bytes of the digest, read as a 32-bit number and divided by 232, give a value between 0 and 1. Lay the entrants end to end in proportion to their weight; that value lands on the winner.

We chose plain SHA-256 over HMAC for exactly this reason — you should not need special tooling to audit us.

What this does and does not prove

It does prove

The winner follows deterministically from a seed we were committed to before the draw, and neither the seed, the entrant list nor the winner has been altered since. Change any one of them and the check fails.

It does not prove

That the entrant list itself was complete or honest — only the person who ran the draw can vouch for who was in it. Publish the commitment and the entrant list before you spin and that gap closes too.

Being straight with you: draws made before provably fair shipped carry an older certificate that only shows the stored record has not been edited. That is worth something, but it is not the same as this, and we will not call it provably fair.