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

8e39048b333acc415e5d4e31ba9068c1efa73bdece835d4d1da60145e69f6ef0

Seed

2229306db00acb026437f9c43fa21fcba8ba18e1e93aa7e0435e8ee7c7b88c43 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

0046c1e67fec2079992d99492dc715e2

Commitment

Batch 55,249, Merkle root 2ad5c3592620f6b785123394f69164288dc8d3c51010c1b72f69e5e7e719efb2. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 82c514755ebd22adf704ba006dcfa70c109f9b14330ec4eb66393b27d62193c7
2. a6d6ab9082a828fb40592d691ef44282ec9da4a3ea1a0dabc251a3166d1db36a
3. cb981adeb5622c563000d3168bbd42719636cf2cf2fc81d7708e93cf69d45846

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.