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

c555edcf6cde0352c55b2ff4ced70ce5ad786e69a8f8a630779cc4bdacb805ce

Seed

411c31f69841a19593c746c3d643f7aa7360cfc08ee218cd7e41e90cd0e24383 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

179b295c68909a9fecaf384bb453f82f

Commitment

Batch 54,050, Merkle root 82b75cb38cea37eec9286b158b4e8aa85c0dbed10aa8a1b8809afef4e710db58. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. c3a7679c2f3ed295009579cbcc33e5df97e734a68fa2f52be8baa4fe1c988e97
2. f84c2dc0d7baaec789d5abbebe33726875c8c0c4ade171df980790342e76b4da
3. 990cd28df3c43f8e6932065c89ec87389ffd174910bc516d526295cb35ca5991

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.