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

6330db6224edaa4ff37e28105458a3e1baa92eef9a624be743a85fefe68fc1b9

Seed

99eb27982f89eca3ddac81b58119220063e06a57d0542cdc15f80282135667f9 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

bf749dd4dbd60ec99d75021691ba9f35

Commitment

Batch 50,350, Merkle root 099d665ad8434911cf7627ebe513b8aa744e358dc692227d59619d37273561bd. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. f35b11ace13a32480b951578a2d8feb8f9d5ee8c35de970a7d802f4409e792c1
2. a6e5dc4a4424dad77d2e1992fb4e47a6961d6591690bfd9b1a6fd9968f8d3d3b

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.