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

d738f2fc12d73732932e812c63374ad7be2d73f8fe063b3795c7ad478d6967b3

Seed

f5af0cd3467daaf6b45b1a7953711a29e46f9709e254a5e5e852d3eab3c81514 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

d21f7383e484058a8a91782d44bcd871

Commitment

Batch 57,345, Merkle root 0b90f6094f498bb7600c6622be8a27c5787482c9d954f4ec4a9070b5326a95e5. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. f0db18f0e7bcaf275cf344f969af0c5bf03f14234a7bca481da20e7aa75979cc
2. 57faaa4e5477643e369eb1a103e0dbc7ea3875d675e8dd0961277545e404f197

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.