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

fad8ce48271825b5b33b9c7ead9b50e138b554221aff6a9297d1e2b1e20a80ee

Seed

bce32289bcd0e0acd12fe9665a6cc734bc9aa56e3b90510a5ba644821bd8ea55 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c882cbdfc43050e9d746d9bce0d45527

Commitment

Batch 58,435, Merkle root 01c355a3d11a59ee764d2826ff8f0a0a9c8af1d2cc01dde3fca48fb5832133e5. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 24187f7f1b9f221be447c48661ba121713b91be33c3d80c2c06fc59814001dcb
2. 9970ed0b4174ba9a500e08f7f7612b7c4aa84ed2c515c189288c34f8ee19ab7e
3. 3a229e7840a6c75355eead3b0ceb78c2c79234e0326198117ec69f0cad69d8cc

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.