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

0ccc55cad7f04a7a028c5977bafc562060ddf52242de344d18325b97f95503b5

Seed

400aaa511dc023728612e3d36883580f3037c57e99c2439327cbff8bada7a44f SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

c70d245f39949134b46dbe849596699f

Commitment

Batch 69,221, Merkle root 5ee25373ccee6da93f2dfa553a4e325c9725ea0b8d92da3a4beed7054c59255b. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. fea4bebb3b2bf9496e9abb85ee23eae08896128c5baf10cf4fdbf35f21c02c5e
2. 2f8af7f6ac69b93e133dc681447dc04557e51be3c5c0bd4d25007bf8aa74756b
3. 704f7f66a54612e5b836e30a04941efaf1da0d8a6e0d177300a65b6a55783647

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.