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

0eebec08eeb147ce43504954d4dd5a8f9974bc49efc6e78c16b7d8d9b720d64d

Seed

9f7ca7b84e278e3abfbcd4b382c983bd7c345a736ec32191278dcd4137ce949d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

706b1f91b6802352caa10c823c3d1a9b

Commitment

Batch 60,482, Merkle root 094e42c0faea2f6449c51cc85444ffd4674c8309a8f815f8dfe2e8ba878ea1bb. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 8c108f853a1fc4cea1f7312562257dfd1ab9109e667ec938bd9e45d901610c9c
2. 6fc245ffd9e32d377add6b2f955c9e30c8fb5dbad5ddce59a60cba055bf78c3b
3. 28422c73f6d8132918416695b5199c5d1d972c322c875ed5a5f58daeaef5430b

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.