commit–reveal

Check it yourself

Every outcome comes from HMAC-SHA256(serverSeed, clientSeed:nonce:cursor). You are shown the hash of the server seed before you bet, and the seed itself when you rotate — so you can check afterwards that we could not have changed anything.

Verify a bet

runs in your browser, no server involved

Game

House edge (bps)

Server seed (revealed)

Server seed hash (published before the bet)

Client seed

Nonce

Bet parameters (JSON)

You can also reproduce the first step by hand: printf "%s" "$SEED" | shasum -a 256 must equal the published hash.

Reference vectors

this build matches the published vectors

Known inputs with known outputs, recomputed by the code running in your browser. Anything that implements sha256 and HMAC-SHA256 should reproduce these — check them against your own tools rather than taking ours on trust.

Server seed (input)

Client seed : nonce : cursor

test:0:0

sha256(serverSeed)✓

60e05bd1b195af2f94112fa7197a5c88289058840ce7c6df9693756bc6250f55

HMAC block✓

c07c6fe56b1ebb2b65b37dac23e1c9a2e9f5238bbcd1736b9106631e0f986c10

Reproduce the first line yourself: printf "%s" "00000000…" | shasum -a 256. The full set lives in packages/fairness/VECTORS.md.