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

63610f91180889591c23ee0bf402fcc18aedcd27d96f1ae7d90844e0a0b7e77e

Seed

7fbed13172f9db55b11e95a3a67c024419eedbf93f90af1994f8bc92216129b8 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e871cbb8410a885af5102aa9a1055533

Commitment

Batch 64,983, Merkle root 1c86b450085e5d7f1affa96ce20b30e6541b0c98fc56a16ab2363b98da148607. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 9cc515fae740ef6c31af659b678049b5c02d9f56c6580baaf0a2e097bcb2b49f
2. c6ca9fbe5f18bafbc40d75052a5a0517fb14d256ebdbb85e5eefad98f451a6d6

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.