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

97fe20826d1f7d2f428afbf42d0d14dd39d9257166daeb01ae7d67cdecc05e6f

Seed

5bdf45e63edb78fcbb259271244284c794369ef781009f17438d17aff14d1884 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

89793447562b723601d871d254a69c4f

Commitment

Batch 57,723, Merkle root 52a3f9fa2ab11fe7ef0eeed4c2d582eef5126eb76469b708cfd9108e54b5473a. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 19199ea2e98bb534ae3046e60c23fd63c166ed222317896742b36f772c4fd95a
2. 9e2137f7b00feaddf64a3f4d315a737b89bb25d7004738237f5e66562e351dfd

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.