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

bd21e6f829452cc9da12be801e9e92c51142200faf7fe73cf9247ea66a7ec002

Seed

c884f65e37fd9d9248fa8ee07ce7b4b68570e02d66d77449d9ee3869b6b349db SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

6aafbd15257384b444985d5ca681ad1d

Commitment

Batch 61,067, Merkle root f9b3db587c45ae504bb5c1518525754798344c93789ae29b4b3a7daed7f995d2. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. b8df8a65b383b500d2724032036fcdb4e01ef8db6aebe8201e41bbf1224f8716
2. 687cd44216058303422408dcf7248e7ac97559d804896300d9c7fb37cca5bed5
3. ea4d6e54913277d1fa7bc21ad4ab5c495b5f938faef035f432eb43575c823081

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.