Provably-fair proof

This page reproduces the winner computation from public inputs. You can recompute every step in your browser's DevTools — don't trust our math, verify it.

1. Pre-commit (server_seed_hash)

Published when the lotto went live (2026-04-16T07:35:29.485Z).

7e44cec0fcd6ae1208006fd18f143b9c4afcee53fd7d9bbb43632c171c1e31b7

2. Reveal (server_seed)

Revealed after draw (2026-04-17T17:53:49.818Z).

46d091271b37fbdc8fc259bf976e378beb42de15bba4041b8aeb923970cf031c

Hash check: ✓ sha256(server_seed) === published hash

3. Client seed inputs (all sold tickets)

#	Wallet	Winner?
10	did:pr...1fei
11	did:pr...1fei
12	did:pr...1fei
13	did:pr...1fei	🎉
18	did:pr...1fei
21	did:pr...1fei
26	did:pr...1fei
27	did:pr...1fei
28	did:pr...1fei
29	did:pr...1fei
34	did:pr...1fei
42	did:pr...1fei
50	did:pr...1fei

4. Derived client_seed

client_seed = sha256(sorted by entry_number, joined as "N:wallet" with '|')

421c6992c7503ea0939ea4eab276ad142943d26bf716ad3d088a7b4901b6ea0d

5. External entropy (Bitcoin block)

Mixed into the HMAC input so the draw depends on a value the operator could not have known when the server seed was committed ( 2026-04-16T07:35:29.485Z). Any Bitcoin block mined after the commit works — we take the tip at draw time.

sourcemempool.spaceheight945,503hash000000000000000000013b92be651a8dacc65df22e940c9c7efbfbf22289a287block time2026-04-17T17:50:09.000Z

Cross-check on mempool.space or blockstream.info.

6. Winner computation

HMAC-SHA256(server_seed, "client_seed:lotto_id:source:height:hash"), first 16 hex chars, mod sold_count (13).

hmac = 164f9229c59e06356a2fd932623c9f520fecc13ed991220728e9bce66346f468

Computed index: 3 → winning entry: #13

7. Independent verification

Show JS snippet (paste into DevTools)

const seed = "46d091271b37fbdc8fc259bf976e378beb42de15bba4041b8aeb923970cf031c";
const hashStr = "7e44cec0fcd6ae1208006fd18f143b9c4afcee53fd7d9bbb43632c171c1e31b7";
const clientSeed = "421c6992c7503ea0939ea4eab276ad142943d26bf716ad3d088a7b4901b6ea0d";
const lottoId = "b085d3d3-7051-4d67-a341-5600892bf490";
const sold = 13;
const entropy = "mempool.space:945503:000000000000000000013b92be651a8dacc65df22e940c9c7efbfbf22289a287";

async function run() {
  const enc = new TextEncoder();
  const seedBytes = enc.encode(seed);
  const hashed = await crypto.subtle.digest("SHA-256", seedBytes);
  const recomputed = [...new Uint8Array(hashed)]
    .map((b) => b.toString(16).padStart(2, "0")).join("");
  console.log("hashOk:", recomputed === hashStr);

  const key = await crypto.subtle.importKey(
    "raw", seedBytes, { name: "HMAC", hash: "SHA-256" }, false, ["sign"]
  );
  const message = entropy
    ? clientSeed + ":" + lottoId + ":" + entropy
    : clientSeed + ":" + lottoId;
  const sig = await crypto.subtle.sign("HMAC", key, enc.encode(message));
  const hex = [...new Uint8Array(sig)]
    .map((b) => b.toString(16).padStart(2, "0")).join("");
  const idx = Number(BigInt("0x" + hex.slice(0, 16)) % BigInt(sold));
  console.log("hmac:", hex);
  console.log("winnerIndex:", idx);
}
run();