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

360e95b8813654f46f63e49ec86c22c28fd05ed96df9e1aaf4d6d81cb58e00ab

Seed

a137f7fa044aef5043515cd0beb03c5f812b9772800e35b0b4018b931d2dacd6 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

e7906b25f141d270e9a4481bb9f0c92d

Commitment

Batch 53,268, Merkle root 30544e4dc5cb9b8beec263b5a6784e144637e7673750f34f7596b45490e1da53. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. c30961cbf98c369848b07cfcd2cfb5f41d0c6988c542ec4073e86cae504ed503
2. 7380c016a5a48486ac728046ca08a5a087597bf5413631d1686ece59edc045f8

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.