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

3fc9c30931b9365c8c2ea9e1d53563f54c954db9d30b0e9e70c2b1debcbb10f0

Seed

67796648fd4bf39f16b5b42ca25cd3d5b93c4a16abebe5c80d62709a5714d11d SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

5bd4d18fb25137e94a192d9648a153e2

Commitment

Batch 64,046, Merkle root f410d3c5854e8ce3a11a8bc79f25984dc79839973c72056bea1b1bbca8cb2aa6. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. fad617a7aac3c27c08812246653909f867087f20fd227a0a1adc9b64671d1efd
2. 9123ea0992aec1eecdf1febbb17c00f8fbb0d4ba74d6f5307916d0b357ab4c53
3. 9c2b99165cdd10f44a1f461312884ee8f0cd18d04564e036843518bb5925c4d7

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.