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

3dae89eb7e383030be811c776bf7f292e7b3d577058d822cb515417111eea044

Seed

ff36b3f0074dba90e42f63b8bbc02bccca884f17bf519d52a8db631b6ff3956d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c9a057874294cae1495e048057fdcc23

Commitment

Batch 59,026, Merkle root ae036ad612fd64e6dac07529f182980ca8c035163a1d265844394f93ccba23ae. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 9ff83b9ca3774a545f138acfda6428d1aba7e17f45cb0bb713141c9ebee3243e
2. 4ca436c3a15bab24a846bfb0f9a6cc7b34ab4be6a3abba88dc8644f1145c028d
3. b8497ef9594e9c868457379722833a549763a79bece9c4683c879995e2044120

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.