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

b7ca1b6607d148cda1b98112d6a71033d60660d93a80efbf2d3ca660a3a5326d

Seed

b382759f22e77109829cdcd8911042cab94eed127059750a10789f21fd2103c5 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

7cb0eade3175ade7d2b78326a1afea9f

Commitment

Batch 62,905, Merkle root ac57a7842c74b7c35956f6c259d637d9ed88ebc15ffeb0bb8846d997d0c47e32. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. b5526afd586cf1330bd9919d615bf2242c2b88e38f9e06ceccdf16e54a3e931a
2. 4fcc12add2c198dc7ffc283182731e25d7d0f23c665604fcf62379b82882684a

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.