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

2a5b33fa5baee75e17dc573426a9feb671afae8bb319edbe7d60790280a64a30

Seed

7ce75b14aac35e03d0a2ad9113f84d46547e6da0cbf4b7ac646939f11912209e SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

9d8c2aff740c0e63841d278aef07c32b

Commitment

Batch 67,300, Merkle root 7c17fe64256f96dbe1ad3d69e0b7534e84dfed69168fa9d2595ec1c821805a3c. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 3480cf31cec57c22515184df49cd011f8352edd9b12bd6332754ce890a8919be
2. 04ca422604374fc989663bfe2c3e3d7310e37324bd1408100017fc22c66413a2
3. cdd786aace06e8cd64b25f6a079a31b8f94793002b278bda0d3444297d97eb3e

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.