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

56f9d7fffff87ef9621e687a0e3be890608e886bd8525acbc50235de0c897354

Seed

5f60eb2c083a67be5f8c306a2e9d83de6c35e7cf682f9ca9f9080a59f7fb5f45 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

23c2d4313b7c6c71c3df5b0d3f1e84f6

Commitment

Batch 52,636, Merkle root ed78deff90b9d21d4925e0f37c780711857d0417bfca54c0bce79d09e95a945b. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. e33f590fae19ff47845735e1bc9e976c29e013eff4678f6d67997fa19063f50b
2. db8562d316516b487cab80edd2480f9511dae654d5cd33365ed04fa16bcb6385
3. e8a3b23c0fb16132702d6fd41311792d02bfa83f2bdbcfdc031234f821dd92d1

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.