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

a16d9dd354b8c0617092a8afe590edf050df51892986017854a891f70db49c03

Seed

43cf5ac4e23582ea8fd9fa55960b65042ecb6dc36bf0fc532d9004235c69ab59 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c518a6a1fb3b3814d3af731bede647e6

Commitment

Batch 53,104, Merkle root e899b82054bc463533b8fc2f6885fefa304bd40d75d4828bd8cd202c57d516d4. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 6c28c3d18e089152f325b16ac2fa760226397e26b102cbfe222b98d6ac96ecfb
2. 4f57665f44d9f1a994479bc56c35821e3428d7e5dc6ab1a7fdd04c0562b3b31c
3. 0aa91823e46984b760213086e878593d1b62b6bc99712f07c7b7d7c37d886d0a

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.