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

185821c7efcbfb72e30ace349cda4527ec588972d1c01cadff39a390bfb98c90

Seed

53d46e355478af678f7eccf3cc243f12b02ea0791eee667fda6494a951838196 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

97937c6f6410432019f1de16b047965d

Commitment

Batch 54,601, Merkle root 8e4ee3985536c049907aae314d687ce18c67f5744413c523534349723fcf4ee3. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 9b7b2c55996f4fec8c788613a2f1d13ee7fb370c1652e81d684c3353e95af754
2. 2ac4b4c185812dea7443faedee127e3731c3fb2ae49fe847d7b9a930388856ac
3. 9c03abb294d4df29d7592c0f4e6a69f5e4e9a931ba57357e53c8b5ffafbe9c51

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.