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

832fb2481ea30cdc57da1bf016561f21a1d8d2a29056b08d026fd3e7b6f59f30

Seed

c22632b6538a397a3a50113496c570cc53a77442953739fa4e6c42adff24ae1a SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

fb7ab2620447ce87bd389169e2502845

Commitment

Batch 51,873, Merkle root 17ae60e3c2dfe445589726d657ce7b161687fb94a95c2f4b5826b249b4c6a6cd. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 4eccab199986b09c9d0ea63c74375f2a01e7bc3fe6a2b85e55e7e5d7e197f148
2. 40ad4dcd4a9b72cf62e9bdbc8b452333fa1d32c0e759faafd85130183498ce72
3. 207a56a0285b0bfb9317c3fbfaebb8ca0af5a752e69448e1faffd9d57ba5cfe0

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.