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

f6547a23916cfd7363690cf79e1c65a452d02532f6db436d03bbe0c09818f71e

Seed

fdeca05e06c98ead9a9661b3a84fbae3a8d50af4ba70139428d397c34282f44c SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

d14eb5aeb1c7be1af6810477853e0bf5

Commitment

Batch 57,487, Merkle root b30d13379d5a9ddab06a5a7f75896275157e1d04d7cfbd4c3ed6b615b3849671. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. da061e7cc74e664f5b3c36cdd6dc699839502a78f6993f4e384551343d97c969
2. 680ec73ee57fa7fd40974638ae0c53e9a62b3a6c2a624fa67bbca6997941033e
3. 9d9a44455a16b68ef193e28251ed27d108711c4af5ebdf9706396176cd964bde

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.