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

e900c87e96d62e69021e4ea34da4fac0c66ebcee5a02b73e59ebb5b7dffea471

Seed

cb8d0c189a6fe4d561807197e7796c38738c078cf59924c2a53031a5db7544f5 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

45cd8d9acb1d7df2aab8a333d63e31f3

Commitment

Batch 53,217, Merkle root a1fa08a2942d6dcd8560fe40a6222b871984733216b9048cedb9f7feba054b40. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 8306d864cd40aa4eb0e1388bcc2a3a8f81dd4392e751f02d0338993f08e94fda
2. 7cf1573b75680933de1711dba5ed83247afd183a5281e6953c14873ad3fd3984

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.