Blackjack

Provably fair

Verify fairness

The session's seed decides every card. Its hash was committed before the first hand; the seed is revealed when the session ends. Each round's cards come from HMAC-SHA256 keyed by the seed over the round's number and the bettor's own seed.

Seed hash

08ac33e8b016f61d3b91c2f9a37093ee713e652c5310fcc82acfa5663827589c

Seed

a31c32be9da726656d9e889cc0afa26c783f5ed309a109d8254d5293a10816ae SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

01a542c96781babc14d3af3c0546a04f

Commitment

Batch 70,877, Merkle root 2a12ec897abdcca389d0c93a89eb6cedbc0824f3886918ee5c4f350118a10b17. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 42d9cc41850da7248513e21461a11629517c90fc186ddf66c8320adba321a9b2
2. fbbad5c860f88e2b94403ad343e6a4e2ef69cec2aa5d19f6da10befa58bbbd77
3. ac09c9eabac81c3bf9ee1954a19ef0f789344bfc775553f22032f8078eb61a23

Checked: the seed hash proves into the root.

To check it yourself, take the session's proof:

1. Hash the seed as above and compare it with the seed hash; prove the seed hash into the root with the Merkle path (keccak256, as for every match).
2. For each round: round seed = HMAC-SHA256(key = seed, "degen.house.round.v1" ‖ 0x00 ‖ u64be(length of the bettor's seed) ‖ bettor's seed ‖ u64be(round)).
3. Key ChaCha20 (RFC 8439, zero nonce) with the round seed and read little-endian 64-bit words; a card is the next word below 2⁶⁴ − 1 − ((2⁶⁴ − 1) mod 52), modulo 52.
4. Replay the round's actions with the game's rules: the cards and the payout must match.

The replay plays every hand rebuilt this way on the server from the same data, and marks any that does not rebuild as recorded.