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

79b3f21b5e1eb79c5671b22a9a6120f7a31b78e8d328976a34f16834d9c1401e

Seed

ab05264629af3c909fd2d3242f991d61adc9d3006fc96a06703c435bd43b123b SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

cda2d91978f85e78079d7c494230c7cb

Commitment

Batch 66,554, Merkle root fdc738e5cd3a3903d344abb4d3975e49a1d1607d44215a73af18ca575c2fa170. Recorded by Degen Protocol; on-chain publication is not available yet. See this batch and its Merkle tree

Merkle path

1. 2c740e2db97b8874c427abf0e8bd9c47729047f690d72d6b3e2b625f3659851b
2. 313a69577f1ac49b30d476e4eadb5d090969ddced6d05a24a1e5e05eb22f1ca9

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.