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

42460858ae3a8f9999b993144f7bad1258535f0be94221415adc178e435e28ea

Seed

19dfba93d0a4c02b0f49ce103203afbcc5e6b21b609ecbc6f49656de13d05230 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

a18581e761362155a1b7710c98ccb51b

Commitment

Batch 58,911, Merkle root cd490459767e253e48b622c85f34472506195fe18331225fa11c0bae3d0bf903. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 99b3b842f8be641f468e62172da30c75ca53abea7cc0a8661f3fff2a365c3036
2. 92d8ad245db39894c7581979f932f4850de40c16a6f06ba33190907b13ddd0b8

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.