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

785c59806aea391a5641bc0c9b24ce04dad945b48b4fa7b20618e2cebf0db640

Seed

71dfe3de71b48f219c817e61f638c08739a098c93b94a1b88f95603acfb0839d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

cdd3b76fa9985568233abb68049b0b2d

Commitment

Batch 61,844, Merkle root 0e5fc856e0883859711e665030556b3f54b1d04bb5d709b2d626c35bc71698f9. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. bc7c59696a4c0a14b99c0236ffb3957c9563f450875f9034f74a5ccec54fca23
2. bfa7f05686fd2a8a7fdd707048e146d1b114eed6610baa3afb2fec8a49662722
3. 17c75e7c3f616a4009aeb4ff9155e0493c098cff7238a49d143b1c7b1fe9ef01

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.