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

7b3595772efdb58747627bb09e00682987ab4859e40916faca9c5c9b593e25a5

Seed

e7df5808e896c7d25f8170066b380f4ea7ebc2dade5305c4628b6f36928a90eb SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

5d933eac54547fe95652ee4fe5610e38

Commitment

Batch 61,255, Merkle root 45d9073fad51d38f9639b8b8c22e86cc1ef65da5c0eb8a0f271bbe06cb9e3225. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 5260b20ed6c79fc78fb32ba0bf59b9d5c505d207a35c8d764ce2df22b5db1f9d
2. 5c33684832d8bd737d97f53fb2e980c19a5dc8c0354b6608a046f87393c5e28c

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.