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

30ac99bd6746ffb1ff0d0ed8ea4036f02f1043bc43008b2cfa29b76dd4aa2751

Seed

62105402b28ba60e1fa5a3a97164b7ad594a32ada9586840a639032d034e0a8d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

18a365c27841dc0dcc9d4d92e8a2271c

Commitment

Batch 49,728, Merkle root 963ef63297937d2a8a41016c187f0912e965516bab942581889a6c7344c5225d. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. 0cfa505980fc4e84b2d6c41a6b13145293800b6b3a0b04dad7a68ca32250f69f
2. d784991b250cc0fceb76a20966e8ee8804012fdfffb268f9b5c6e5fac640d551
3. b3f9ea36ad843c00abd11f317a90935187fc44fdc00cff72a1683fd93379bf1d

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.