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

373fee969e14411ecf53d9706c8b8505dc10b87ca59ca309bfe2d7543cfbc27b

Seed

0375da0ee1ec4de60d586a6c27f21a4cf22e6951353f3ee5553ded87ea7c63e3 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

002650c9802ac61fdbb121bc101aafdf

Commitment

Batch 55,651, Merkle root 67af18f95313e87dbf666f8c3c3746e82b2866b88328afccf27494377926c44d. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 0b023e57cdb73d841ef237aae34f23ba0fdd0ee4cf5f1e513f34c3affdd78785

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.